mmc: pci: Add CONFIG_MMC_PCI

We don't want pci_mmc to compile every time x86 compiles, only when
there's a platform that needs it. For that reason, we're adding a new
CONFIG_MMC_PCI which platforms can choose to enable.

Suggested-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
diff --git a/configs/theadorable-x86-dfi-bt700_defconfig b/configs/theadorable-x86-dfi-bt700_defconfig
index cde33bb..1703cee 100644
--- a/configs/theadorable-x86-dfi-bt700_defconfig
+++ b/configs/theadorable-x86-dfi-bt700_defconfig
@@ -47,6 +47,7 @@
 CONFIG_DM_I2C=y
 CONFIG_NUVOTON_NCT6102D=y
 CONFIG_MMC=y
+CONFIG_MMC_PCI=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_SDMA=y
 CONFIG_SPI_FLASH=y