x86: minnowmax: Adjust U-Boot environment address in SPI flash

Currently U-Boot environment address is at offset 0x7fe00 of a 8MB
SPI flash. When creating a partial u-boot.rom image without flash
descriptor and ME firmware, U-Boot actually occupies the last 1MB
of the flash, and reprograming U-Boot causes previous environment
settings get lost which is not convenient during testing.

Adjust the environment address to 0x6ef000 instead (before the MRC
cache data region in the flash).

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

doc/README.x86

@@ -304,12 +304,12 @@ Offset   Description         Controlling config
 000000   descriptor.bin      Hard-coded to 0 in ifdtool
 001000   me.bin              Set by the descriptor
 500000   <spare>
+6ef000   Environment         CONFIG_ENV_OFFSET
 6f0000   MRC cache           CONFIG_ENABLE_MRC_CACHE
 700000   u-boot-dtb.bin      CONFIG_SYS_TEXT_BASE
 790000   vga.bin             CONFIG_VGA_BIOS_ADDR
 7c0000   fsp.bin             CONFIG_FSP_ADDR
 7f8000   <spare>             (depends on size of fsp.bin)
-7fe000   Environment         CONFIG_ENV_OFFSET
 7ff800   U-Boot 16-bit boot  CONFIG_SYS_X86_START16
 
 Overall ROM image size is controlled by CONFIG_ROM_SIZE.

include/configs/minnowmax.h

@@ -40,6 +40,6 @@
 #define CONFIG_X86EMU_RAW_IO
 
 #define CONFIG_ENV_SECT_SIZE		0x1000
-#define CONFIG_ENV_OFFSET		0x007fe000
+#define CONFIG_ENV_OFFSET		0x006ef000
 
 #endif	/* __CONFIG_H */