gpu: nvgpu: add accessor for gr_class_error

Add accessors to read class error code from
NV_PGRAPH_CLASS_ERROR

Bug 200010403

Change-Id: Ia99f50e264f9b8aa93f99994e52424418a2e4f74
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/419565
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

drivers/gpu/nvgpu/gk20a/hw_gr_gk20a.h

@@ -146,6 +146,14 @@ static inline u32 gr_fecs_intr_r(void)
 {
 	return 0x00400144;
 }
+static inline u32 gr_class_error_r(void)
+{
+	return 0x00400110;
+}
+static inline u32 gr_class_error_code_v(u32 r)
+{
+	return (r >> 0) & 0xffff;
+}
 static inline u32 gr_intr_nonstall_r(void)
 {
 	return 0x00400120;