hostapd: Refactor Channel Switch Wrapper element generation

hostapd: Refactor Channel Switch Wrapper element generation

The Wide Bandwidth Channel Switch subelement was directly appended in
the Channel Switch Wrapper element function
hostapd_eid_wb_chsw_wrapper(). However, a subsequent change would add
Bandwidth Indication subelement in the Channel Switch Wrapper element.
Hence using the same function name would be confusing.

Hence, refactor the current code into two functions. The first function
hostapd_eid_chsw_wrapper() forms the channel switch wrapper element.
This calls hostapd_eid_wb_channel_switch() to add a Wide Bandwidth
Channel Switch subelement inside it.

No functionality change.

Signed-off-by: Karthik M <quic_karm@quicinc.com>
Signed-off-by: Aditya Kumar Singh <quic_adisi@quicinc.com>