arch: common: guard the compilation of sw_isr_common with CMakeLists.txt

Instead of using a macro guard to prevent functions in
`sw_isr_common.c` from getting compiled when
`CONFIG_DYNAMIC_INTERRUPTS` isn't enabled, do that in
`CMakeLists.txt` instead.

Signed-off-by: Yong Cong Sin <ycsin@meta.com>