Paul Barker authored Oct 05, 2022 and Heinrich Schuchardt committed Oct 16, 2022

This function is already defined in spi.h but no implementation of it
currently exists in the tree. The implementation is based on the static
function spi_set_speed_mode(). The function prototype is modified so
that an success or error condition can be returned to the caller.

Signed-off-by: Paul Barker <paul.barker@sancloud.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>