drm/gma500: remove unused gma_pipe_event function

clang with W=1 reports
drivers/gpu/drm/gma500/psb_irq.c:35:19: error: unused function
  'gma_pipe_event' [-Werror,-Wunused-function]
static inline u32 gma_pipe_event(int pipe)
                  ^
This function is not used, so remove it.
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230319142320.1704336-1-trix@redhat.com

drivers/gpu/drm/gma500/psb_irq.c

@@ -32,17 +32,6 @@ static inline u32 gma_pipestat(int pipe)
 	BUG();
 }
 
-static inline u32 gma_pipe_event(int pipe)
-{
-	if (pipe == 0)
-		return _PSB_PIPEA_EVENT_FLAG;
-	if (pipe == 1)
-		return _MDFLD_PIPEB_EVENT_FLAG;
-	if (pipe == 2)
-		return _MDFLD_PIPEC_EVENT_FLAG;
-	BUG();
-}
-
 static inline u32 gma_pipeconf(int pipe)
 {
 	if (pipe == 0)