staging: mt7621-mmc: Fix typo in function parameters

The type pm_message does not exist in the kernel, the correct type is
pm_message_t, so the type of the parameter is corrected.

Fixes: 9673d9f6 ("staging: mt7621-mmc: Refactor suspend, resume")
Signed-off-by: Christian Lütke-Stetzkamp <christian@lkamp.de>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>