wifi: cw1200: fix __le16 sparse warnings

Sparse warns:

drivers/net/wireless/st/cw1200/cw1200_spi.c:83:17:    got restricted __le16 [usertype]
drivers/net/wireless/st/cw1200/cw1200_spi.c:148:17: warning: incorrect type in assignment (different base types)
drivers/net/wireless/st/cw1200/cw1200_spi.c:148:17:    expected unsigned short [addressable] [assigned] [usertype] regaddr
drivers/net/wireless/st/cw1200/cw1200_spi.c:148:17:    got restricted __le16 [usertype]

These cpu_to_le16() calls are not really making any sense to me. On a big
endian system we first convert regaddr from big to little using cpu_to_le16()
but immediately after we convert them back to big endian? So just remove them.

Compile tested only.

Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240130151556.2315951-4-kvalo@kernel.org