drm/radeon/cayman: add some missing regs to the VM reg checker

These regs were being wronly rejected leading to rendering
issues.

fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=56876

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>

drivers/gpu/drm/radeon/evergreen_cs.c

@@ -2725,6 +2725,9 @@ static bool evergreen_vm_reg_valid(u32 reg)
 	/* check config regs */
 	switch (reg) {
 	case GRBM_GFX_INDEX:
+	case CP_STRMOUT_CNTL:
+	case CP_COHER_CNTL:
+	case CP_COHER_SIZE:
 	case VGT_VTX_VECT_EJECT_REG:
 	case VGT_CACHE_INVALIDATION:
 	case VGT_GS_VERTEX_REUSE:

drivers/gpu/drm/radeon/evergreend.h

@@ -91,6 +91,10 @@
 #define		FB_READ_EN					(1 << 0)
 #define		FB_WRITE_EN					(1 << 1)
 
+#define	CP_STRMOUT_CNTL					0x84FC
+
+#define	CP_COHER_CNTL					0x85F0
+#define	CP_COHER_SIZE					0x85F4
 #define	CP_COHER_BASE					0x85F8
 #define	CP_STALLED_STAT1			0x8674
 #define	CP_STALLED_STAT2			0x8678