const'ify flashctx to align signatures with cros flashrom

The ChromiumOS flashrom fork has since const'ify flashctx
in a few places. This aligns the function signatures to
match with downstream to ease forward porting patches
out of downstream back into mainline flashrom.

This patch is minimum viable alignment and so feedback is
welcome.

Change-Id: Iff6dbda13cb0d941481c0d204b9c30895630fbd1
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/40324
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/spi.c b/spi.c
index 489baf3..aed2a92 100644
--- a/spi.c
+++ b/spi.c
@@ -26,7 +26,7 @@
 #include "programmer.h"
 #include "spi.h"
 
-int spi_send_command(struct flashctx *flash, unsigned int writecnt,
+int spi_send_command(const struct flashctx *flash, unsigned int writecnt,
 		     unsigned int readcnt, const unsigned char *writearr,
 		     unsigned char *readarr)
 {
@@ -34,12 +34,12 @@
 				       readarr);
 }
 
-int spi_send_multicommand(struct flashctx *flash, struct spi_command *cmds)
+int spi_send_multicommand(const struct flashctx *flash, struct spi_command *cmds)
 {
 	return flash->mst->spi.multicommand(flash, cmds);
 }
 
-int default_spi_send_command(struct flashctx *flash, unsigned int writecnt,
+int default_spi_send_command(const struct flashctx *flash, unsigned int writecnt,
 			     unsigned int readcnt,
 			     const unsigned char *writearr,
 			     unsigned char *readarr)
@@ -60,7 +60,7 @@
 	return spi_send_multicommand(flash, cmd);
 }
 
-int default_spi_send_multicommand(struct flashctx *flash,
+int default_spi_send_multicommand(const struct flashctx *flash,
 				  struct spi_command *cmds)
 {
 	int result = 0;