ARM64: simplify cpu_read_bootcpu_ops using OF/DT helper

Once the cpu_logical_map for any logical cpu is populated with the
corresponding physical identifier(i.e. mpidr), it's device node can
be retrieved using the DT helper 'of_get_cpu_node'. Currently the
device tree parsing code to get boot cpu node is duplicated in
'cpu_read_bootcpu_ops'.

This patch replaces the code parsing the device tree for the boot
cpu with of_get_cpu_node.

Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-commit: 248f0e7f5f0012fb9c1954e582196aa7f32a0c81
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Ian Maund <imaund@codeaurora.org>