drm/buddy: stop using PAGE_SIZE

The drm_buddy minimum page-size requirements should be distinct from the
CPU PAGE_SIZE. Only restriction is that the minimum page-size is at
least 4K.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240229105112.250077-3-matthew.auld@intel.com


Signed-off-by: Christian König <christian.koenig@amd.com>