Convert CONFIG_SKIP_LOWLEVEL_INIT et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SKIP_LOWLEVEL_INIT
   CONFIG_SKIP_LOWLEVEL_INIT_ONLY

In order to do this, we need to introduce SPL and TPL variants of these
options so that we can clearly disable these options only in SPL in some
cases, and both instances in other cases.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/cpu/arm1136/start.S b/arch/arm/cpu/arm1136/start.S
index da7278e..4bc27f6 100644
--- a/arch/arm/cpu/arm1136/start.S
+++ b/arch/arm/cpu/arm1136/start.S
@@ -39,7 +39,7 @@
 	msr	cpsr,r0
 
 	/* the mask ROM code should have PLL and others stable */
-#ifndef CONFIG_SKIP_LOWLEVEL_INIT
+#if !CONFIG_IS_ENABLED(SKIP_LOWLEVEL_INIT)
 	bl  cpu_init_crit
 #endif
 
@@ -62,7 +62,7 @@
  *
  *************************************************************************
  */
-#ifndef CONFIG_SKIP_LOWLEVEL_INIT
+#if !CONFIG_IS_ENABLED(SKIP_LOWLEVEL_INIT)
 cpu_init_crit:
 	/*
 	 * flush v4 I/D caches
@@ -81,7 +81,7 @@
 	orr	r0, r0, #0x00001000	@ set bit 12 (I) I-Cache
 	mcr	p15, 0, r0, c1, c0, 0
 
-#ifndef CONFIG_SKIP_LOWLEVEL_INIT_ONLY
+#if !CONFIG_IS_ENABLED(SKIP_LOWLEVEL_INIT_ONLY)
 	/*
 	 * Jump to board specific initialization... The Mask ROM will have already initialized
 	 * basic memory.  Go here to bump up clock rate and handle wake up conditions.
@@ -91,4 +91,4 @@
 	mov	lr, ip		/* restore link */
 #endif
 	mov	pc, lr		/* back to my caller */
-#endif /* CONFIG_SKIP_LOWLEVEL_INIT */
+#endif /* !CONFIG_IS_ENABLED(SKIP_LOWLEVEL_INIT) */