meta-asrock: Generalize MMC/SDHCI reset quirk

As it turns out, e3c256d4i isn't the only board with this problem,
so move the u-boot config fragment to meta-common and make it available
via an override.

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Change-Id: I7182a6a1dd12603fec1d0633edc60d018285914f
diff --git a/meta-asrock/meta-common/recipes-bsp/u-boot/u-boot-common-aspeed-sdk.inc b/meta-asrock/meta-common/recipes-bsp/u-boot/u-boot-common-aspeed-sdk.inc
new file mode 100644
index 0000000..fd129d2
--- /dev/null
+++ b/meta-asrock/meta-common/recipes-bsp/u-boot/u-boot-common-aspeed-sdk.inc
@@ -0,0 +1,3 @@
+FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
+
+SRC_URI:append:asrock-mmc-sdhci-reset-quirk = " file://disable-mmc-sdhci.cfg"