Update PSRAM cache flush algorithm #2462

Job	Run time
Spelling, Style, Boards, Package	1m 22s
Build PlatformIO Examples	4m 12s
Mac (macOS-12)	4m 59s
Build 0	8m 5s
Build RP2350 0	7m 17s
Build 1	7m 40s
Mac (macOS-14)	2m 40s
Build RP2350 1	7m 8s
Build 2	8m 40s
Build RP2350-RISCV 0	6m 55s
Build RP2350 2	8m 28s
Build 3	9m 10s
Build RP2350 3	7m 11s
Build TinyUSB Examples	4m 25s
Build RP2350-RISCV 1	7m 22s
Build 4	8m 29s
Build RP2350 4	7m 50s
Build RP2350-RISCV 2	7m 48s
Build 5	8m 48s
Build RP2350 5	8m 0s
Build RP2350-RISCV 3	7m 0s
Build Every Variant 0	8m 8s
Build RP2350-RISCV 4	7m 31s
Build Every Variant 1	7m 2s
Windows	3m 57s
Build RP2350-RISCV 5	8m 6s
	2h 58m 13s

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