soc/intel/alderlake: Add eMMC device into chipset.cb

Add eMMC device into chipset.cb and keep it `off` by default.
eMMC device is applicable only for Alder Lake N SOC.

Change-Id: I2bc38ee5814688409feb7e4531c1daa5b54953c0
Signed-off-by: Krishna Prasad Bhat <krishna.p.bhat.d@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61065
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Kangheui Won <khwon@chromium.org>
Reviewed-by: Rizwan Qureshi <rizwan.qureshi@intel.com>

src/soc/intel/alderlake/chipset.cb

@@ -185,6 +185,8 @@ chip soc/intel/alderlake
 		device pci 19.0 alias i2c4 off end
 		device pci 19.1 alias i2c5 off end
 		device pci 19.2 alias uart2 off end
+		# eMMC device is applicable only for ADL-N
+		device pci 1a.0 alias emmc off end
 		device pci 1c.0 alias pcie_rp1 off end
 		device pci 1c.1 alias pcie_rp2 off end
 		device pci 1c.2 alias pcie_rp3 off end