drm/vc4: replace idr_init() by idr_init_base()

idr_init() uses base 0 which is an invalid identifier for this driver.
The idr_alloc for this driver uses VC4_PERFMONID_MIN as start value for
ID range and it is #defined to 1. The new function idr_init_base allows
IDR to set the ID lookup from base 1. This avoids all lookups that
otherwise starts from 0 since 0 is always unused / available.

References: commit 6ce711f ("idr: Make 1-based IDRs more efficient")

Signed-off-by: Deepak R Varma <mh12gx2825@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20201105202135.GA145111@localhost

drivers/gpu/drm/vc4/vc4_perfmon.c

@@ -77,7 +77,7 @@ struct vc4_perfmon *vc4_perfmon_find(struct vc4_file *vc4file, int id)
 void vc4_perfmon_open_file(struct vc4_file *vc4file)
 {
 	mutex_init(&vc4file->perfmon.lock);
-	idr_init(&vc4file->perfmon.idr);
+	idr_init_base(&vc4file->perfmon.idr, VC4_PERFMONID_MIN);
 }
 
 static int vc4_perfmon_idr_del(int id, void *elem, void *data)