phytec_phycore_imx27_common_init() doesn't need to be __naked, because
the stack has already been setup. What we want to have though is the
noinline attribute to make sure phytec_phycore_imx27_common_init() is
indeed a separate function which is called with initialized stack.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>