nvmxip: move header to include

Move header to include to allow external code
to get the internal bdev structures to access
block device operations.

as at it, just add the UCLASS_NVMXIP string
so we get the correct output in partitions
listing.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
diff --git a/drivers/mtd/nvmxip/nvmxip.h b/include/nvmxip.h
similarity index 100%
rename from drivers/mtd/nvmxip/nvmxip.h
rename to include/nvmxip.h
diff --git a/test/dm/nvmxip.c b/test/dm/nvmxip.c
index e934748..89bf481 100644
--- a/test/dm/nvmxip.c
+++ b/test/dm/nvmxip.c
@@ -17,7 +17,7 @@
 #include <linux/bitops.h>
 #include <test/test.h>
 #include <test/ut.h>
-#include "../../drivers/mtd/nvmxip/nvmxip.h"
+#include <nvmxip.h>
 
 /* NVMXIP devices described in the device tree */
 #define SANDBOX_NVMXIP_DEVICES 2