ARM: 9168/1: Add support for Cortex-M55 processor

Add processor info object for ARM Cortex-M55 CPU which inherits the
setup procedure, the processor and cache operation function from
Cortex-M7 processor info object.

Signed-off-by: Tigran Tadevosyan <tigran.tadevosyan@arm.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>