flashrom.c: Make need_erase() helper static local

The need_erase() helper is only used within flashrom.c

Change-Id: Ic0946bb109fca2fc18e15eefa11cccea284ded0b
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/64369
Original-Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Original-Reviewed-by: Thomas Heijligen <src@posteo.de>
Original-Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/71460
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 caee351..1048164 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -463,8 +463,8 @@
  * @gran	write granularity (enum, not count)
  * @return      0 if no erase is needed, 1 otherwise
  */
-int need_erase(const uint8_t *have, const uint8_t *want, unsigned int len,
-               enum write_granularity gran, const uint8_t erased_value)
+static int need_erase(const uint8_t *have, const uint8_t *want, unsigned int len,
+		      enum write_granularity gran, const uint8_t erased_value)
 {
 	int result = 0;
 	unsigned int i;