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/drivers/mmc/Makefile b/drivers/mmc/Makefile
index 6a488f1..1e8d23f 100644
--- a/drivers/mmc/Makefile
+++ b/drivers/mmc/Makefile
@@ -34,7 +34,7 @@
 obj-$(CONFIG_MMC_OMAP_HS)		+= omap_hsmmc.o
 obj-$(CONFIG_MMC_MXC)			+= mxcmmc.o
 obj-$(CONFIG_MMC_MXS)			+= mxsmmc.o
-obj-$(CONFIG_X86) += pci_mmc.o
+obj-$(CONFIG_MMC_PCI)			+= pci_mmc.o
 obj-$(CONFIG_PXA_MMC_GENERIC) += pxa_mmc_gen.o
 obj-$(CONFIG_SUPPORT_EMMC_RPMB) += rpmb.o
 obj-$(CONFIG_S3C_SDI) += s3c_sdi.o