MIPS: Netlogic: Add nlm_get_boot_data() helper

This moves the calculation and casting needed to access the CPU initialization
data to a function nlm_get_boot_data()

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5426/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>