realtek_mst_i2c_spi.c: Consolidate shifts to the one fn

To avoid further incorrect mappings ensure all the shifting
happens within realtek_mst_i2c_spi_map_page() itself.

BUG=none
BRANCH=none
TEST=builds

Change-Id: I96c595b1abae044347fb0c2c91b891a60dd3675e
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Suggested-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/48975
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
1 file changed