riscv: remove unused riscv_error_t type (#539)

This seems to be completely unused in these two files. It was probably
accidentally copied from riscv-011.c, where it is used.

Change-Id: I3f7ad8b2d26b005d3ea4438e2b3ec46a6c801792
Signed-off-by: Thomas Hebb <tommyhebb@gmail.com>

src/target/riscv/riscv-013.c

@@ -111,12 +111,6 @@ typedef enum {
 	DMI_STATUS_BUSY = 3
 } dmi_status_t;
 
-typedef enum {
-	RE_OK,
-	RE_FAIL,
-	RE_AGAIN
-} riscv_error_t;
-
 typedef enum slot {
 	SLOT0,
 	SLOT1,

src/target/riscv/riscv.c

@@ -68,12 +68,6 @@ typedef enum {
 #define DBUS_DATA_SIZE				34
 #define DBUS_ADDRESS_START			36
 
-typedef enum {
-	RE_OK,
-	RE_FAIL,
-	RE_AGAIN
-} riscv_error_t;
-
 typedef enum slot {
 	SLOT0,
 	SLOT1,