Kconfig: Convert CONFIG_SYS_SRAM_SIZE to Kconfig

This converts ad-hoc CONFIG_SYS_SRAM_SIZE to Kconfig.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
diff --git a/Kconfig b/Kconfig
index 9f7707a..583d39d 100644
--- a/Kconfig
+++ b/Kconfig
@@ -395,6 +395,13 @@
 	default 0x80000000 if TARGET_PIC32MZDASK
 	default 0x0
 
+config SYS_SRAM_SIZE
+	hex
+	default 0x00080000 if TARGET_PIC32MZDASK
+	default 0x10000 if TARGET_DEVKIT8000
+	default 0x10000 if TARGET_TRICORDER
+	default 0x0
+
 endmenu		# General setup
 
 menu "Boot images"