staging: vt6656: vnt_rf_write_embedded add reg length and IFREGCTL_REGW

The rf register always have  *_REG_LEN and IFREGCTL_REGW macros added.

*_REG_LEN is always 23(0x17) replace them with VNT_RF_REG_LEN.

Remove *_REG_LEN and IFREGCTL_REGW from tables and vnt_rf_set_txpower and
apply VNT_RF_REG_LEN and IFREGCTL_REGW in vnt_rf_write_embedded

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>