beta-uboot: Enter fastboot automatically

See b/128999798

Change-Id: I374d089cf824989177a86a2697685463675a806d
diff --git a/board/freescale/imx8mq_phanbell/imx8m_phanbell.c b/board/freescale/imx8mq_phanbell/imx8m_phanbell.c
index d42e2ba..b150456 100644
--- a/board/freescale/imx8mq_phanbell/imx8m_phanbell.c
+++ b/board/freescale/imx8mq_phanbell/imx8m_phanbell.c
@@ -347,7 +347,8 @@
         "echo Please follow the instructions at g.co/coral/setup.;"
         "echo;"
         "echo;"
-        "mmc partconf 0 0 1 1;";
+        "mmc partconf 0 0 1 1;"
+        "fastboot 0;";
 	setenv("bootcmd", bootscript);
 #endif