programmer: Smoothen register_par_master API

It was impossible to register a const struct par_master that would
point to dynamically allocated `data`. Fix that so that we won't
have to create more mutable globals.

BUG=b:185191942
TEST=builds

Change-Id: I95bc92f6c54c5bcdac1c522ca87054aaffed0f40
Signed-off-by: Anastasia Klimchuk <aklm@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/54169
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
diff --git a/atavia.c b/atavia.c
index b407a30..e04950a 100644
--- a/atavia.c
+++ b/atavia.c
@@ -160,7 +160,7 @@
 		return 1;
 	}
 
-	register_par_master(&lpc_master_atavia, BUS_LPC);
+	register_par_master(&lpc_master_atavia, BUS_LPC, NULL);
 
 	return 0;
 }