ARM: OMAP2+: prm44xx: Fix section annotation on omap44xx_prm_enable_io_wakeup

When building the kernel with Clang, the following section mismatch
warning appears:

WARNING: vmlinux.o(.text+0x38b3c): Section mismatch in reference from
the function omap44xx_prm_late_init() to the function
.init.text:omap44xx_prm_enable_io_wakeup()
The function omap44xx_prm_late_init() references
the function __init omap44xx_prm_enable_io_wakeup().
This is often because omap44xx_prm_late_init lacks a __init
annotation or the annotation of omap44xx_prm_enable_io_wakeup is wrong.

Remove the __init annotation from omap44xx_prm_enable_io_wakeup so there
is no more mismatch.

Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>