treewide: Drop most cases of `sizeof(struct ...)`

Spelling out the struct type name hurts readability and introduces
opportunities for bugs to happen when the pointer variable type is
changed but the corresponding sizeof is (are) not.

Tested: `make CONFIG_EVERYTHING=yes CONFIG_JLINK_SPI=no VERSION=none -j`
with and without this patch; the flashrom executable does not change.

flashrom-stable: Applied partially.

Change-Id: Icc0b60ca6ef9f5ece6ed2a0e03600bb6ccd7dcc6
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/55266
Original-Reviewed-by: Nico Huber <nico.h@gmx.de>
Original-Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/71371
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/fmap.c b/fmap.c
index ca25651..e13de67 100644
--- a/fmap.c
+++ b/fmap.c
@@ -195,7 +195,7 @@
 	if (prepare_flash_access(flashctx, true, false, false, false))
 		return 1;
 
-	fmap = malloc(sizeof(struct fmap));
+	fmap = malloc(sizeof(*fmap));
 	if (!fmap) {
 		msg_gerr("Out of memory.\n");
 		goto _free_ret;