drivers: counter: esp32: Fix alarm stops working

Fix condition in which alarm stops working after a certain amount
of time. Hardware timer is 54-bit, yet it is treated as 32-bit by
the counter driver. To allow alarm event by hardware comparators,
counter high word must be loaded into the register along with
the lower word managed by the driver.

Signed-off-by: Raffael Rostagno <raffael.rostagno@espressif.com>