[ROM] functionalities in asm code

### Description

The rom_start.S asm file implements lot of functionalities (interrupt, reset, RMA, Power, watchdog, clock, memory init) in asm code. is there specific reasons for implementing them in asm ?

Can they be moved to C code ?

Start by reading rom_start.S and mapping its interrupt, reset, RMA, power, watchdog, clock, and memory-init functionality. Then investigate the reasons these routines use assembly and assess whether moving them to C is feasible; the issue provides no tests or concrete completion criteria.

Written by the indexing model from the issue text.