arch: arm: use dt and UCLASS_SYSCON to get gic lpi details

Use device tree and UCLASS_SYSCON driver to get
Generic Interrupt Controller (GIC) lpi address and
maximum GIC redistributors count.

Also update Kconfig to select REGMAP and SYSCON when
GIC_V3_ITS is enabled.

Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e04a2c6..3e11ddf 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -64,6 +64,8 @@
 
 config GIC_V3_ITS
 	bool "ARM GICV3 ITS"
+	select REGMAP
+	select SYSCON
 	help
 	  ARM GICV3 Interrupt translation service (ITS).
 	  Basic support for programming locality specific peripheral