spl: Refactor spl_load_info->read to use units of bytes

Simplify things a bit for callers of spl_load_info->read by refactoring it
to use units of bytes instead of bl_len. This generally simplifies the
logic, as MMC is the only loader which actually works in sectors. It will
also allow further refactoring to remove the special-case handling of
filename.  spl_load_legacy_img already works in units of bytes (oops) so it
doesn't need to be changed.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/test/image/spl_load_os.c b/test/image/spl_load_os.c
index 49edf15..794cfad 100644
--- a/test/image/spl_load_os.c
+++ b/test/image/spl_load_os.c
@@ -16,14 +16,13 @@
 	int fd;
 };
 
-static ulong read_fit_image(struct spl_load_info *load, ulong sector,
-			    ulong count, void *buf)
+static ulong read_fit_image(struct spl_load_info *load, ulong offset,
+			    ulong size, void *buf)
 {
 	struct text_ctx *text_ctx = load->priv;
-	off_t offset, ret;
+	off_t ret;
 	ssize_t res;
 
-	offset = sector * load->bl_len;
 	ret = os_lseek(text_ctx->fd, offset, OS_SEEK_SET);
 	if (ret != offset) {
 		printf("Failed to seek to %zx, got %zx (errno=%d)\n", offset,
@@ -31,14 +30,14 @@
 		return 0;
 	}
 
-	res = os_read(text_ctx->fd, buf, count * load->bl_len);
+	res = os_read(text_ctx->fd, buf, size);
 	if (res == -1) {
 		printf("Failed to read %lx bytes, got %ld (errno=%d)\n",
-		       count * load->bl_len, res, errno);
+		       size, res, errno);
 		return 0;
 	}
 
-	return count;
+	return size;
 }
 
 static int spl_test_load(struct unit_test_state *uts)