drm/radeon: make missing smc ucode non-fatal (r7xx-SI)

Prevent driver load problems if the smc is missing.

bug:
https://bugzilla.kernel.org/show_bug.cgi?id=63011

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Tested-by: Mikko Rapeli <mikko.rapeli@iki.fi>
Cc: stable@vger.kernel.org
diff --git a/drivers/gpu/drm/radeon/si.c b/drivers/gpu/drm/radeon/si.c
index d4652af..d96f7cb 100644
--- a/drivers/gpu/drm/radeon/si.c
+++ b/drivers/gpu/drm/radeon/si.c
@@ -1681,6 +1681,7 @@
 		       fw_name);
 		release_firmware(rdev->smc_fw);
 		rdev->smc_fw = NULL;
+		err = 0;
 	} else if (rdev->smc_fw->size != smc_req_size) {
 		printk(KERN_ERR
 		       "si_smc: Bogus length %zu in firmware \"%s\"\n",