dummyflasher.c: Inline data fetch for spi workers

The spi callbacks do not need par logic to fetch the
data field. Instead of going though get_data_from_context()
just fetch 'data' directly out of mst.spi.

This leads us towards a path of removing dummy_buses_supported
from global state.

BUG=none
BRANCH=none
TEST=`./flashrom -r /tmp/fwupdater.apnSQQ -p dummy:emulate=VARIABLE_SIZE,image=test_update.sh.tmp.emu,size=8388608`

Change-Id: I63b8d8861df75f52f241f09614146990fdfe59ed
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/54906
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sam McNally <sammc@google.com>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
diff --git a/dummyflasher.c b/dummyflasher.c
index 4661f3d..587fc61 100644
--- a/dummyflasher.c
+++ b/dummyflasher.c
@@ -129,7 +129,7 @@
 
 static int dummy_spi_write_256(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
 {
-	struct emu_data *emu_data = get_data_from_context(flash);
+	struct emu_data *emu_data = flash->mst->spi.data;
 	return spi_write_chunked(flash, buf, start, len,
 				 emu_data->spi_write_256_chunksize);
 }
@@ -570,7 +570,7 @@
 				  unsigned char *readarr)
 {
 	unsigned int i;
-	struct emu_data *emu_data = get_data_from_context(flash);
+	struct emu_data *emu_data = flash->mst->spi.data;
 	if (!emu_data) {
 		msg_perr("No data in flash context!\n");
 		return 1;