dfu: rename dfu_tftp_write() to dfu_write_by_name()

This function is essentially independent from tftp, and will also be
utilised in implementing UEFI capsule update in a later commit.
So just give it a more generic name.
In addition, a new configuration option, CONFIG_DFU_WRITE_ALT, was
introduced so that the file will be compiled with different options,
particularly one added in a later commit.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/include/dfu.h b/include/dfu.h
index 84abdc7..a4cd86c 100644
--- a/include/dfu.h
+++ b/include/dfu.h
@@ -494,27 +494,27 @@
 #endif
 
 /**
- * dfu_tftp_write() - write TFTP data to DFU medium
+ * dfu_write_by_name() - write data to DFU medium
+ * @dfu_entity_name:	Name of DFU entity to write
+ * @addr:		Address of data buffer to write
+ * @len:		Number of bytes
+ * @interface:		Destination DFU medium (e.g. "mmc")
+ * @devstring:		Instance number of destination DFU medium (e.g. "1")
  *
- * This function is storing data received via TFTP on DFU supported medium.
+ * This function is storing data received on DFU supported medium which
+ * is specified by @dfu_entity_name.
  *
- * @dfu_entity_name:	name of DFU entity to write
- * @addr:		address of data buffer to write
- * @len:		number of bytes
- * @interface:		destination DFU medium (e.g. "mmc")
- * @devstring:		instance number of destination DFU medium (e.g. "1")
- *
- * Return:		0 on success, otherwise error code
+ * Return:		0 - on success, error code - otherwise
  */
-#if CONFIG_IS_ENABLED(DFU_TFTP)
-int dfu_tftp_write(char *dfu_entity_name, unsigned int addr, unsigned int len,
-		   char *interface, char *devstring);
+#if CONFIG_IS_ENABLED(DFU_WRITE_ALT)
+int dfu_write_by_name(char *dfu_entity_name, unsigned int addr,
+		      unsigned int len, char *interface, char *devstring);
 #else
-static inline int dfu_tftp_write(char *dfu_entity_name, unsigned int addr,
-				 unsigned int len, char *interface,
-				 char *devstring)
+static inline int dfu_write_by_name(char *dfu_entity_name, unsigned int addr,
+				    unsigned int len, char *interface,
+				    char *devstring)
 {
-	puts("TFTP write support for DFU not available!\n");
+	puts("write support for DFU not available!\n");
 	return -ENOSYS;
 }
 #endif