defconfigs: Add config for DRA7xx High Security EVM with USB Boot support

Add a new defconfig file for the DRA7xx High Security EVM. This config
is specific for the case of USB booting.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 69131e4..aa13aed 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -721,6 +721,7 @@
 F:	configs/am43xx_hs_evm_defconfig
 F:	configs/am57xx_hs_evm_defconfig
 F:	configs/dra7xx_hs_evm_defconfig
+F:	configs/dra7xx_hs_evm_usb_defconfig
 F:	configs/k2hk_hs_evm_defconfig
 F:	configs/k2e_hs_evm_defconfig
 F:	configs/k2g_hs_evm_defconfig