fbdev: aty: fix missing indentation in if statement

There is a missing indentation following an if statement, fix this.

Detected by Coccinelle:
drivers/video/fbdev/aty/mach64_ct.c:183:2-15: code aligned with
following code on line 184

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>