gpu/amd: vega10_hwmgr: fix inappropriate private variable name

In file vega10_hwmgr.c, the names of struct vega10_power_state *
and struct pp_power_state * are confusingly used, which may lead
to some confusion.

Status quo is that variables of type struct vega10_power_state *
are named "vega10_ps", "ps", "vega10_power_state". A more
appropriate usage is that struct are named "ps" is used for
variabled of type struct pp_power_state *.

So rename struct vega10_power_state * which are named "ps" and
"vega10_power_state" to "vega10_ps", I also renamed "psa" to
"vega10_psa" and "psb" to "vega10_psb" to make it more clearly.

The rows longer than 100 columns are involved.

Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Meng Tang <tangmeng@uniontech.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>