ARM: mach-imx: mx3: Fix section mismatch in imx3_init_l2x0()

Fix the following section mismatch:

WARNING: vmlinux.o(.text+0x11be8): Section mismatch in reference from the function imx3_init_l2x0() to the function .init.text:l2x0_init()
The function imx3_init_l2x0() references
the function __init l2x0_init().
This is often because imx3_init_l2x0 lacks a __init
annotation or the annotation of l2x0_init is wrong.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>