Avoid the implicit dev_priv local variable use, and pass dev_priv
explicitly to the PSR2_SU_STATUS register macro.

v2: Expand from _PSR2_SU_STATUS to PSR2_SU_STATUS (Rodrigo)
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240502103925.1829104-1-jani.nikula@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>