aspeed: move MTD partition rules

Move the MTD partition rules to their own recipe under
udev rather than appending u-boot-fw-utils.  Additionally
the rules are an artifact of the aspeed u-boot-fw-utils
configuration, so place the new recipe in the aspeed layer.

Tested: Built a witherspoon image
Change-Id: I1fec995dd75543b2630db29d78bfb29a1a5949d5
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/common/recipes-bsp/u-boot/u-boot-fw-utils_2016.07.bb b/common/recipes-bsp/u-boot/u-boot-fw-utils_2016.07.bb
index 2631499..9bba67e 100644
--- a/common/recipes-bsp/u-boot/u-boot-fw-utils_2016.07.bb
+++ b/common/recipes-bsp/u-boot/u-boot-fw-utils_2016.07.bb
@@ -34,3 +34,5 @@
 
 PACKAGE_ARCH = "${MACHINE_ARCH}"
 BBCLASSEXTEND = "cross"
+
+RDEPENDS_${PN} = "udev-aspeed-mtd-partitions"