sys_io: arc: Add sys_in*/sys_out* functions

This functions - reusing _arc_v2_aux_reg_* ones - will ease porting
drivers to ARC architecture hiding arch specific calls under generic
functions. On ARC, auxiliary registers is conceptually comparable to
x86 ports, thus the possibility to bring sys_in/sys_out to access those.

Change-Id: Ic5c0fc41f32ec4ad861dbb58cd8defaf4497bc03
Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>