cris: lower the printk level in cris serial driver

KERN_CRIT is too high, replace those KERN_CRIT with KERN_ERR or KERN_WARNING.

Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>