staging: octeon: convert cvmx_spi_mode_t from typedef to plain enum

staging: octeon: convert cvmx_spi_mode_t from typedef to plain enum

The Linux kernel coding style discourages the use of typedefs for
enums. Convert cvmx_spi_mode_t to a plain 'enum cvmx_spi_mode' and
update all users across the MIPS Octeon architecture code and the
staging driver stubs.

This is part of a series converting all remaining enum typedefs in
the octeon subsystem to plain enums, improving compliance with the
kernel coding style.

No functional change.

Signed-off-by: Eric Wu <kunjinkao.jp@gmail.com>
Link: https://patch.msgid.link/20260427155427.668540-2-kunjinkao.jp@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>