timer: mchp-pit64b: add support for pit64b

Add support for Microchip PIT64B timer. The timer is 64 bit length and
is used as a free running counter (in continuous mode with highest values
for period registers). The clock feeding the timer would be no more
than 12.5MHz.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
diff --git a/drivers/timer/Makefile b/drivers/timer/Makefile
index c22ffeb..3a4d74b 100644
--- a/drivers/timer/Makefile
+++ b/drivers/timer/Makefile
@@ -22,3 +22,4 @@
 obj-$(CONFIG_STM32_TIMER)	+= stm32_timer.o
 obj-$(CONFIG_X86_TSC_TIMER)	+= tsc_timer.o
 obj-$(CONFIG_MTK_TIMER)		+= mtk_timer.o
+obj-$(CONFIG_MCHP_PIT64B_TIMER)	+= mchp-pit64b-timer.o