mmc-omap: add missing '\n'

This patch add a missing '\n' at the end of the 'cover is open' string
in mmc_omap_switch_handler().

Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>