SMBIOS: Avoid sizeof on struct type

Where applicable, use the size of the associated variable.

Change-Id: Ibbac2a82893232a6f87182a6a965b84a599d633e
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55904
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Michał Żygowski <michal.zygowski@3mdeb.com>

src/drivers/elog/elog.c

@@ -594,7 +594,7 @@ static inline u8 *elog_flash_offset_to_address(void)
 int elog_smbios_write_type15(unsigned long *current, int handle)
 {
 	struct smbios_type15 *t = (struct smbios_type15 *)*current;
-	int len = sizeof(struct smbios_type15);
+	int len = sizeof(*t);
 	uintptr_t log_address;
 
 	size_t elog_size = region_device_sz(&elog_state.nv_dev);