net: l2: wifi: Modify btwt_setup usage.

Soft ap supports WIFI_BTWT_AGREEMENT_MAX BTWT sessions.
The BTWT parameters for each session can be different.

The current usage can only set one set of parameters.
All sessions follow this set of parameters.

Add enhance code to support setting different
BTWT parameters for every sessions.

Usage:
wifi twt btwt_setup <sta_wait> <offset>
<twtli> <session_num>
<id0> <mantissa0> <exponent0> <nominal_wake0>
<id1> <mantissa1> <exponent1> <nominal_wake1>
<idx> <mantissax> <exponentx> <nominal_wakex>
The total number of '0, 1, ..., x' is session_num

For example:
wifi twt btwt_setup 0 0 0 2 0 112 10 128 1 32 10 64

Signed-off-by: Qiankun Li <qiankun.li@nxp.com>