use 128 MB for ramsize (needs small qemu patch)

target/sh/kernel/qemu-sh

@@ -4,7 +4,7 @@ CONFIG_CPU_SH4=y
 CONFIG_CPU_HAS_PMU=y
 CONFIG_CPU_SUBTYPE_SH7751R=y
 CONFIG_MEMORY_START=0x0c000000
-CONFIG_MEMORY_SIZE=0x04000000
+CONFIG_MEMORY_SIZE=0x08000000
 CONFIG_29BIT=y
 CONFIG_VSYSCALL=y
 CONFIG_PAGE_SIZE_4KB=y