MAINTAINERS: Update AMD POWERPLAY pattern

commit e098bc9612 ("drm/amd/pm: optimize the power related source code layout")
moved the directory, update the F: file pattern to match.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

MAINTAINERS

@@ -927,7 +927,7 @@ M:	Evan Quan <evan.quan@amd.com>
 L:	amd-gfx@lists.freedesktop.org
 S:	Supported
 T:	git git://people.freedesktop.org/~agd5f/linux
-F:	drivers/gpu/drm/amd/powerplay/
+F:	drivers/gpu/drm/amd/pm/powerplay/
 
 AMD SEATTLE DEVICE TREE SUPPORT
 M:	Brijesh Singh <brijeshkumar.singh@amd.com>