ARM: omap2: remove incorrect __init annotation

omap3xxx_prm_enable_io_wakeup() is marked __init, but its caller is not, so
we get a warning with clang-8:

WARNING: vmlinux.o(.text+0x343c8): Section mismatch in reference from the function omap3xxx_prm_late_init() to the function .init.text:omap3xxx_prm_enable_io_wakeup()
The function omap3xxx_prm_late_init() references
the function __init omap3xxx_prm_enable_io_wakeup().
This is often because omap3xxx_prm_late_init lacks a __init
annotation or the annotation of omap3xxx_prm_enable_io_wakeup is wrong.

When building with gcc, omap3xxx_prm_enable_io_wakeup() is always
inlined, so we never noticed in the past.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/mach-omap2/prm3xxx.c

@@ -433,7 +433,7 @@ static void omap3_prm_reconfigure_io_chain(void)
  * registers, and omap3xxx_prm_reconfigure_io_chain() must be called.
  * No return value.
  */
-static void __init omap3xxx_prm_enable_io_wakeup(void)
+static void omap3xxx_prm_enable_io_wakeup(void)
 {
 	if (prm_features & PRM_HAS_IO_WAKEUP)
 		omap2_prm_set_mod_reg_bits(OMAP3430_EN_IO_MASK, WKUP_MOD,