gpu/drm/radeon: Fix typo in comments

Remove the repeated word 'and' from comments
Signed-off-by: Jiang Jian <jiangjian@cdjrlc.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/r300_reg.h

@@ -1103,7 +1103,7 @@
  * The destination register index is in FPI1 (color) and FPI3 (alpha)
  * together with enable bits.
  * There are separate enable bits for writing into temporary registers
- * (DSTC_REG_* /DSTA_REG) and and program output registers (DSTC_OUTPUT_*
+ * (DSTC_REG_* /DSTA_REG) and program output registers (DSTC_OUTPUT_*
  * /DSTA_OUTPUT). You can write to both at once, or not write at all (the
  * same index must be used for both).
  *