Properly indicate ISR number in SystemView

[khutchens]

Is your enhancement proposal related to a problem? Please describe.
When recording traces via SystemView, all ISRs share IRQ number 0, which makes ISR tracing pretty useless.

Describe the solution you'd like
SystemView should show the individual ISR as separate traces with the correct IRQ numbers.

This is a pretty easy change since the SystemView tracing backend already provides sysview_get_interrupt(), which propogates the current interrupt number (not currently set) back to SystemView. All that's needed is a hook in isr_wrapper.S:158 (and other configurations) to set the current IRQ number during ISR entry.

I'm happy to submit a PR to add this, but I'm not equipped to add or test it for anything other than the CONFIG_ARMV7_M_ARMV8_M_MAINLINE configuration, which would be a pretty incomplete addition.

[nashif]

This was already addressed in 10ee29e