environment: ti: Add get_fit_config command to get FIT config string

When OE is packaging a dtb file into the FIT image it names the node based
on the dtb filename. Node names can't have "/" so it is turned into "_".
We select our FIT config using the "fdtfile" env var so we don't duplicate
the board_name to fdt logic. Result is fdtfile needs mangled when used to
select a config node from OE made FIT image. Do this here.

Signed-off-by: Andrew Davis <afd@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/include/environment/ti/ti_armv7_common.env b/include/environment/ti/ti_armv7_common.env
index 4d33464..0c0929d 100644
--- a/include/environment/ti/ti_armv7_common.env
+++ b/include/environment/ti/ti_armv7_common.env
@@ -20,5 +20,6 @@
 	do;
 	setenv overlaystring ${overlaystring}'#'${overlay};
 	done;
-run_fit=bootm ${addr_fit}#conf-${fdtfile}${overlaystring}
+get_fit_config=setexpr name_fit_config gsub / _ conf-${fdtfile}
+run_fit=run get_fit_config; bootm ${addr_fit}#${name_fit_config}${overlaystring}