REVERT ME: Define CONFIG_BOARD_MRFLD_HVP

REVERT ME: Define CONFIG_BOARD_MRFLD_HVP

BZ: 27386

Merrifield HVP platform only implemented 1 storage
host controller - eMMC0. Other 3 storage host controllers
are not existed in FPGA at all.

So the storage driver needs to know the board type
and prevent initialization to the 3 non-existen
host controllers if on the HVP board.

Actually, the board type macro CONFIG_BOARD_MRFLD_HVP
should be defined in arch/x86/Kconfig and enabled in
Merrifeld board specific configuration file. But now
these changes are not introduced yet. So this patch
just set it in mmc driver to make sure the storage
driver working on HVP board.

Once the macro defined and enabled in board specific
configuration file, this patch should be reverted.

Change-Id: I40f1aef2bbb6c3336cb64aa7fe2fdc734eec5126
Signed-off-by: Yunpeng Gao <yunpeng.gao@intel.com>
Reviewed-on: http://android.intel.com:8080/40287
Reviewed-by: Tang, Richard <richard.tang@intel.com>
Tested-by: Sun, Jianhua <jianhua.sun@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>