src/lib: Remove unnecessary code

Fix the following warnings detected by checkpatch.pl:

WARNING: break is not useful after a goto or return
WARNING: Statements terminations use 1 semicolon
WARNING: else is not generally useful after a break or return
WARNING: void function return statements are not generally useful

TEST=Build and run on Galileo Gen2

Change-Id: I6f095c4e9cb1ee4ff2ebdf095ef612e1a8393231
Signed-off-by: Lee Leahy <Leroy.P.Leahy@intel.com>
Reviewed-on: https://review.coreboot.org/18762
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/lib/jpeg.c

@@ -417,7 +417,6 @@ int jpeg_decode(unsigned char *buf, unsigned char *pic,
 				break;
 			default:
 				return ERR_DEPTH_MISMATCH;
-				break;
 			}
 		}
 	}