common/board_r: arm: Merge initr_enable_interrupts into interrupts_init

initr_enable_interrupts() is an ARM-specific wrapper over
enable_interrupts(), which is run during the common init sequence. It can
be eliminated by moving the enable_interrupts() call to the end of
interrupt_init() function, in arch/arm/lib/interrupts*.c.

Signed-off-by: Ovidiu Panait <ovpanait@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>