arm/arm64: gic: Split check_acked() into two functions

check_acked() has several peculiarities: is the only function among the
check_* functions which calls report() directly, it does two things
(waits for interrupts and checks for misfired interrupts) and it also
mixes printf, report_info and report calls.

check_acked() also reports a pass and returns as soon all the target CPUs
have received interrupts, However, a CPU not having received an interrupt
*now* does not guarantee not receiving an erroneous interrupt if we wait
long enough.

Rework the function by splitting it into two separate functions, each with
a single responsibility: wait_for_interrupts(), which waits for the
expected interrupts to fire, and check_acked() which checks that interrupts
have been received as expected.

wait_for_interrupts() also waits an extra 100 milliseconds after the
expected interrupts have been received in an effort to make sure we don't
miss misfiring interrupts.

Splitting check_acked() into two functions will also allow us to
customize the behavior of each function in the future more easily
without using an unnecessarily long list of arguments for check_acked().

CC: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>