mmc: ftsdc010_mci: fix build error if CONFIG_FTSDC010_SDIO is not defined

mmc: ftsdc010_mci: fix build error if CONFIG_FTSDC010_SDIO is not defined

The FTSDC010_DCR_FIFO_RST symbol is conditionally
defined in <faraday/ftsdc010.h> and it is available
available when CONFIG_FTSDC010_SDIO is enabled.

However the actual driver code unconditionally uses
the FTSDC010_DCR_FIFO_RST constant and this causes
build error if CONFIG_FTSDC010_SDIO is not enabled.

The following error happens when compiling for the
adp-ag101 board:

  ftsdc010_mci.c: In function 'ftsdc010_request':
  ftsdc010_mci.c:178: error: 'FTSDC010_DCR_FIFO_RST' undeclared (first use in this function)
  ftsdc010_mci.c:178: error: (Each undeclared identifier is reported only once
  ftsdc010_mci.c:178: error: for each function it appears in.)

The patch ensures that the FTSDC010_DCR_FIFO_RST
symbol gets used only if CONFIG_FTSDC010_SDIO is
defined.

Compile tested only.

Cc: Kuo-Jung Su <dantesu@faraday-tech.com>
Cc: Macpaul Lin <macpaul@andestech.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Reviewed-by: Kuo-Jung Su <dantesu@faraday-tech.com>