linux-imx: Make the local version use -imx instead of -aiy

Change-Id: I2d58465ebdf954cf3af65503978a8ae6511b82a3
(cherry picked from commit bcd17d3bc84710424d71bbae86ace6e7d8b8c2c8)
diff --git a/rootfs.mk b/rootfs.mk
index 924c9b5..f75c957 100644
--- a/rootfs.mk
+++ b/rootfs.mk
@@ -23,7 +23,7 @@
 	imx-vpu-hantro \
 	imx-vpuwrap \
 	libdrm-vivante \
-	linux-image-4.9.51-aiy \
+	linux-image-4.9.51-imx \
 	python3-edgetpu \
 	python3-edgetpuvision \
 	uboot-imx