arm: dra7: Set fastboot variables in environment

One can obtain those variables using next commands:

    $ fastboot getvar cpu
    $ fastboot getvar secure
    $ fastboot getvar board_rev
    $ fastboot getvar userdata_size

Those variables are needed for fastboot.sh script.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

board/ti/dra7xx/evm.c

@@ -561,6 +561,7 @@ int board_late_init(void)
 		setenv("boot_fit", "1");
 
 	omap_die_id_serial();
+	omap_set_fastboot_vars();
 #endif
 	return 0;
 }