[ARM] arm64: Invalidate I-Cache and TLBs in proc_setup()

The bootloader might run with I-Cache or MMU enabled hence
invalidate both in proc_setup().

If bootloader is using D-Cache too then it is responsiblity
of bootloader to clean-invalidate D-Cache before jumping
into Xvisor (as-per Linux booting protocol).

Signed-off-by: Anup Patel <anup@brainfault.org>