[Silabs] Fix linkage and some apps build for the Sparkfun board

[jmartinez-silabs]

fixes #26357
fixes #26356
fixes #26350

Two recently added files from Silabs SDK needed to be linked for that board.
This board has no buttons, so I added some #ifdef to the button's usage in certain apps.
Removed some include of the buttons header where they were not needed any more thanks to the ongoing silabs platforms abstraction

[github-actions]

PR #26370: Size comparison from 5ff1818 to a147858

Full report (1 build for cc32xx)

platform	target	config	section	5ff1818	a147858	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	604866	604866	0	0.0
			(read/write)	204156	204156	0	0.0
			.ARM.attributes	44	44	0	0.0
			.ARM.exidx	8	8	0	0.0
			.bss	197568	197568	0	0.0
			.comment	206	206	0	0.0
			.data	1468	1468	0	0.0
			.debug_abbrev	957005	957005	0	0.0
			.debug_aranges	101104	101104	0	0.0
			.debug_frame	341416	341416	0	0.0
			.debug_info	19522698	19522698	0	0.0
			.debug_line	2666219	2666219	0	0.0
			.debug_line_str	513	513	0	0.0
			.debug_loc	33340	33340	0	0.0
			.debug_loclists	1488771	1488771	0	0.0
			.debug_ranges	4984	4984	0	0.0
			.debug_rnglists	94291	94291	0	0.0
			.debug_str	3100491	3100491	0	0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	104346	104346	0	0.0
			.shstrtab	265	265	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	482872	482872	0	0.0
			.symtab	287120	287120	0	0.0
			.text	498396	498396	0	0.0

[github-actions]

PR #26370: Size comparison from 5ff1818 to 63663d4

Full report (1 build for cc32xx)

platform	target	config	section	5ff1818	63663d4	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	604866	604866	0	0.0
			(read/write)	204156	204156	0	0.0
			.ARM.attributes	44	44	0	0.0
			.ARM.exidx	8	8	0	0.0
			.bss	197568	197568	0	0.0
			.comment	206	206	0	0.0
			.data	1468	1468	0	0.0
			.debug_abbrev	957005	957005	0	0.0
			.debug_aranges	101104	101104	0	0.0
			.debug_frame	341416	341416	0	0.0
			.debug_info	19522698	19522698	0	0.0
			.debug_line	2666219	2666219	0	0.0
			.debug_line_str	513	513	0	0.0
			.debug_loc	33340	33340	0	0.0
			.debug_loclists	1488771	1488771	0	0.0
			.debug_ranges	4984	4984	0	0.0
			.debug_rnglists	94291	94291	0	0.0
			.debug_str	3100491	3100491	0	0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	104346	104346	0	0.0
			.shstrtab	265	265	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	482872	482872	0	0.0
			.symtab	287120	287120	0	0.0
			.text	498396	498396	0	0.0