mfd: db8500-prcmu: Fix some section annotations

When building the kernel with Clang, the following section mismatch
warnings appear:

WARNING: vmlinux.o(.text+0x7239cc): Section mismatch in reference from
the function db8500_prcmu_probe() to the function
.init.text:init_prcm_registers()
The function db8500_prcmu_probe() references
the function __init init_prcm_registers().
This is often because db8500_prcmu_probe lacks a __init
annotation or the annotation of init_prcm_registers is wrong.

WARNING: vmlinux.o(.text+0x723e28): Section mismatch in reference from
the function db8500_prcmu_probe() to the function
.init.text:fw_project_name()
The function db8500_prcmu_probe() references
the function __init fw_project_name().
This is often because db8500_prcmu_probe lacks a __init
annotation or the annotation of fw_project_name is wrong.

db8500_prcmu_probe should not be marked as __init so remove the __init
annotation from fw_project_name and init_prcm_registers.

Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>