Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/drivers/gpu/drm/radeon/r300.c b/drivers/gpu/drm/radeon/r300.c
index 8713731..55a7f19 100644
--- a/drivers/gpu/drm/radeon/r300.c
+++ b/drivers/gpu/drm/radeon/r300.c
@@ -437,7 +437,7 @@
 	status = RREG32(R_000E40_RBBM_STATUS);
 	dev_info(rdev->dev, "(%s:%d) RBBM_STATUS=0x%08X\n", __func__, __LINE__, status);
 	/* resetting the CP seems to be problematic sometimes it end up
-	 * hard locking the computer, but it's necessary for successfull
+	 * hard locking the computer, but it's necessary for successful
 	 * reset more test & playing is needed on R3XX/R4XX to find a
 	 * reliable (if any solution)
 	 */