move pinmux.h to drivers/pinmux.h and
create a shim for backward-compatibility.
No functional changes to the headers.
A warning in the shim can be controlled with CONFIG_COMPAT_INCLUDES.
Related to #16539
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
FE310 is the name of one SoC out of a range of products in the SiFive
Freedom line. The FE310 SoC port in Zephyr is compatible with all of
these products, so rename the SoC to SiFive Freedom
Signed-off-by: Nathaniel Graff <nathaniel.graff@sifive.com>