omap4/5/am33xx: Make lowlevel_init available to all armv7 platforms

Make the lowlevel_init function that these platforms have which just
sets up the stack and calls a C function available to all armv7
platforms.  As part of this we change some of the macros that are used
to be more clear.  Previously (except for am335x evm) we had been
setting CONFIG_SYS_INIT_SP_ADDR to a series of new defines that are
equivalent to simply referencing NON_SECURE_SRAM_END.  On am335x evm we
should have been doing this initially and do now.

Cc: Sricharan R <r.sricharan@ti.com>
Tested-by: Allen Martin <amartin@nvidia.com>
Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/include/configs/am335x_evm.h b/include/configs/am335x_evm.h
index 2bfe8c6..a8a6b8e 100644
--- a/include/configs/am335x_evm.h
+++ b/include/configs/am335x_evm.h
@@ -148,7 +148,7 @@
 #define CONFIG_MAX_RAM_BANK_SIZE	(1024 << 20)	/* 1GB */
 
 #define CONFIG_SYS_SDRAM_BASE		PHYS_DRAM_1
-#define CONFIG_SYS_INIT_SP_ADDR         (CONFIG_SYS_SDRAM_BASE + 0x1000 - \
+#define CONFIG_SYS_INIT_SP_ADDR         (NON_SECURE_SRAM_END - \
 						GENERATED_GBL_DATA_SIZE)
  /* Platform/Board specific defs */
 #define CONFIG_SYS_TIMERBASE		0x48040000	/* Use Timer2 */
@@ -195,7 +195,7 @@
 #define CONFIG_SPL
 #define CONFIG_SPL_TEXT_BASE		0x402F0400
 #define CONFIG_SPL_MAX_SIZE		(46 * 1024)
-#define CONFIG_SPL_STACK		LOW_LEVEL_SRAM_STACK
+#define CONFIG_SPL_STACK		CONFIG_SYS_INIT_SP_ADDR
 
 #define CONFIG_SPL_BSS_START_ADDR	0x80000000
 #define CONFIG_SPL_BSS_MAX_SIZE		0x80000		/* 512 KB */