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>
1 file changed