stlinkv3_spi: Move a declaration out of for-loop head

GCC 4.8 wants an explicit `-std=c99` or something for this to work. It
seems easier to keep the common declaration style.

Change-Id: Ic0819f82169df4d66cc949494229b0749c06e8f6
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/38034


Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Miklós Márton <martonmiklosqdev@gmail.com>

stlinkv3_spi.c

@@ -333,6 +333,7 @@ static int stlinkv3_spi_transmit(struct flashctx *flash,
 	int rc = 0;
 	int actual_length = 0;
 	uint32_t rw_status = 0;
+	unsigned int i;
 
 	if (stlinkv3_spi_set_SPI_NSS(SPI_NSS_LOW)) {
 		msg_perr("Failed to set the NSS pin to low\n");
@@ -346,7 +347,7 @@ static int stlinkv3_spi_transmit(struct flashctx *flash,
 	command[2] = (uint8_t)write_cnt;
 	command[3] = (uint8_t)(write_cnt >> 8);
 
-	for (unsigned int i = 0; (i < 8) && (i < write_cnt); i++)
+	for (i = 0; (i < 8) && (i < write_cnt); i++)
 		command[4+i] = write_arr[i];
 
 	rc = libusb_bulk_transfer(stlinkv3_handle, STLINK_EP_OUT,