Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/drivers/media/radio/radio-mr800.c b/drivers/media/radio/radio-mr800.c
index e6b2d08..b3a635b 100644
--- a/drivers/media/radio/radio-mr800.c
+++ b/drivers/media/radio/radio-mr800.c
@@ -99,7 +99,7 @@
 
 /*
  * Commands that device should understand
- * List isnt full and will be updated with implementation of new functions
+ * List isn't full and will be updated with implementation of new functions
  */
 #define AMRADIO_SET_FREQ	0xa4
 #define AMRADIO_SET_MUTE	0xab