RISC-V: Factor out common code of __cpu_resume_enter()

The cpu_resume() function is very similar for the suspend to disk and
suspend to ram cases. Factor out the common code into suspend_restore_csrs
macro and suspend_restore_regs macro.

Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230330064321.1008373-3-jeeheng.sia@starfivetech.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>