xtensa: use 128M instead of 64M for qemu

target/xtensa/kernel/qemu-xtensa

@@ -1,5 +1,5 @@
 CONFIG_XTENSA=y
 CONFIG_XTENSA_PLATFORM_XTFPGA=y
 CONFIG_CMDLINE_BOOL=y
-CONFIG_CMDLINE="console=ttyS0,38400 memmap=0x04000000@0"
+CONFIG_CMDLINE="console=ttyS0,38400 memmap=128M@0"
 CONFIG_COMPAT_32BIT_TIME=y