clock-imx35: fix reboot in internal boot mode

commit 8d75a26 "ARM: mx35: use generic function for displaying silicon revision"
disabled IIM clock after reading silicon revision which will prevent
reboot in internal boot mode.

Signed-off-by: Eric Bénard <eric@eukrea.com>
Cc: Jason Liu <jason.hui@linaro.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>