metag: Add JTAG Debug Adapter (DA) support

Add basic JTAG Debug Adapter (DA) support so that drivers which
communicate with the DA can detect whether one is actually present
(otherwise the target will halt indefinitely).

This allows the metag_da TTY driver and imgdafs filesystem driver to be
built, updates defconfigs, and sets up the metag_da console early if
it's configured in.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
diff --git a/arch/metag/configs/meta1_defconfig b/arch/metag/configs/meta1_defconfig
index 837c235..ad663ca 100644
--- a/arch/metag/configs/meta1_defconfig
+++ b/arch/metag/configs/meta1_defconfig
@@ -14,6 +14,7 @@
 # CONFIG_IOSCHED_CFQ is not set
 CONFIG_FLATMEM_MANUAL=y
 CONFIG_META12_FPGA=y
+CONFIG_METAG_DA=y
 CONFIG_HZ_100=y
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
@@ -27,6 +28,8 @@
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
 # CONFIG_LEGACY_PTYS is not set
+CONFIG_DA_TTY=y
+CONFIG_DA_CONSOLE=y
 # CONFIG_DEVKMEM is not set
 # CONFIG_HW_RANDOM is not set
 # CONFIG_HWMON is not set