This commit reworks the Xilinx TTC timer driver to use the "match" mode
instead of the "interval" mode which counts up to the specified value
and resets to zero.
Using the "match" mode ensures that the timer keeps counting even after
an interrupt is triggered, and facilitates the tickless mode support
implementation.
This also allows `z_timer_cycle_get_32` to return the correct cycle
count when interrupt is locked; thereby, fixing the k_busy_wait hang
issue.
Note that the TTC "match" mode emulation (and tickless timer operation)
is only stable when the QEMU icount mode is enabled.
Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
