timers: atmel_pit: introduce CONFIG_SPL_ATMEL_PIT_TIMER

This commit allows the ATMEL_PIT_TIMER driver to be unselected in SPL and be
selected in u-boot proper. The SPL can use a different timer.
By having a separate Kconfig for ATMEL_TCB in SPL, the size of the SPL
decreases by 0.3 KBytes.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index 68e90b8..9205017 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -90,6 +90,15 @@
 	  it is designed to offer maximum accuracy and efficient management,
 	  even for systems with long response time.
 
+config SPL_ATMEL_PIT_TIMER
+	bool "Atmel periodic interval timer support in SPL"
+	depends on SPL_TIMER
+	help
+	  Select this to enable a periodic interval timer for Atmel devices,
+	  it is designed to offer maximum accuracy and efficient management,
+	  even for systems with long response time.
+	  Select this to be available in SPL.
+
 config ATMEL_TCB_TIMER
 	bool "Atmel timer counter support"
 	depends on TIMER