disk: dos: rename write_mbr_partition to write_mbr_sector

write_mbr_partition() function name is a bit misleading, so rename it to
write_mbr_sector(). This is a preparation for adding code for writing a
complete MBR partition layout.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
diff --git a/drivers/fastboot/fb_mmc.c b/drivers/fastboot/fb_mmc.c
index ae8e8e5..4e26cef 100644
--- a/drivers/fastboot/fb_mmc.c
+++ b/drivers/fastboot/fb_mmc.c
@@ -508,7 +508,7 @@
 			fastboot_fail("invalid MBR partition", response);
 			return;
 		}
-		if (write_mbr_partition(dev_desc, download_buffer)) {
+		if (write_mbr_sector(dev_desc, download_buffer)) {
 			printf("%s: writing MBR partition failed\n", __func__);
 			fastboot_fail("writing MBR partition failed",
 				      response);