Kconfig.boot: Make 0x0 the default SYS_TEXT_BASE for POSITION_INDEPENDENT

When we build U-Boot with POSITION_INDEPENDENT we must have
SYS_TEXT_BASE be set to zero.  Make this the default in that case.
Signed-off-by: NTom Rini <trini@konsulko.com>
Reviewed-by: NMark Kettenis <kettenis@openbsd.org>

common/Kconfig.boot

@@ -358,6 +358,7 @@ config HAVE_SYS_TEXT_BASE
 
 config SYS_TEXT_BASE
 	depends on HAVE_SYS_TEXT_BASE
+	default 0x0 if POSITION_INDEPENDENT
 	default 0x80800000 if ARCH_OMAP2PLUS || ARCH_K3
 	default 0x4a000000 if ARCH_SUNXI && !MACH_SUN9I && !MACH_SUN8I_V3S
 	default 0x2a000000 if ARCH_SUNXI && MACH_SUN9I