tree: Make internal functions static

None of these functions are used outside of the files they are defined
in, so make them all static.

Change-Id: Ie9cbe12d289bcedacf2f1bf483ae64ef8039ccc1
Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/33667
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Nico Huber <nico.h@gmx.de>

usbblaster_spi.c

@@ -67,7 +67,7 @@ static struct ftdi_context ftdic;
 
 /* The programmer shifts bits in the wrong order for SPI, so we use this method to reverse the bits when needed.
  * http://graphics.stanford.edu/~seander/bithacks.html#ReverseByteWith32Bits */
-uint8_t reverse(uint8_t b)
+static uint8_t reverse(uint8_t b)
 {
 	return ((b * 0x0802LU & 0x22110LU) | (b * 0x8020LU & 0x88440LU)) * 0x10101LU >> 16;
 }