x86: link: Allow more space for U-Boot

The extra ACPI code increases U-Boot above it current size limit. Move
the start earlier to provide space.
Signed-off-by: NSimon Glass <sjg@chromium.org>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>

configs/chromebook_link_defconfig

 CONFIG_X86=y
-CONFIG_SYS_TEXT_BASE=0xFFF00000
+CONFIG_SYS_TEXT_BASE=0xFFEF0000
 CONFIG_SYS_MALLOC_F_LEN=0x2400
 CONFIG_NR_DRAM_BANKS=8
 CONFIG_ENV_SIZE=0x1000