flashrom.c: replace enum programmer with size_t

Using size_t since programmer_table_size uses ARRAY_SIZE which returns
size_t.

Change-Id: Id2ad9630fbc41e98d182768b553788e069fa5095
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.de>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/55120
Original-Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/71377
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/flashrom.c b/flashrom.c
index 1d376d2..ca271ca 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -1521,7 +1521,7 @@
 	const char *pname;
 	int pnamelen;
 	int remaining = 0, firstline = 1;
-	enum programmer p;
+	size_t p;
 	int i;
 
 	for (p = 0; p < programmer_table_size; p++) {