spi: Add function to probe erase command opcode for all spi_master

Add a field, probe_opcode, to struct spi_master which points to a
function returning a bool by checking if a given command is supported by
the programmer in use. This is used for getting a whitelist of commands
supported by the programmer, as some programmers like ichspi don't
support all opcodes.

Most programmers use the default function, which just returns true.
ICHSPI and dummyflasher use their specialized function.

Change-Id: I6852ef92788221f471a859c879f8aff42558d36d
Signed-off-by: Aarya Chaumal <aarya.chaumal@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/65183
Reviewed-by: Thomas Heijligen <src@posteo.de>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Felix Singer <felixsinger@posteo.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

buspirate_spi.c

@@ -182,6 +182,7 @@ static struct spi_master spi_master_buspirate = {
 	.write_256	= default_spi_write_256,
 	.write_aai	= default_spi_write_aai,
 	.shutdown	= buspirate_spi_shutdown,
+	.probe_opcode	= default_spi_probe_opcode,
 };
 
 static const struct buspirate_speeds spispeeds[] = {