feat(plat/arm/sgi): add CPU specific handler for Neoverse V1

The 'CORE_PWRDN_EN' bit of 'CPUPWRCTLR_EL1' register requires an
explicit write to clear it for hotplug and idle to function correctly.
So add Neoverse V1 CPU specific handler in platform reset handler to
clear the CORE_PWRDN_EN bit.

Signed-off-by: shriram.k <shriram.k@arm.com>
Change-Id: I56084c42a56c401503a751cb518238c83cfca8ac
1 file changed