cfg80211/nl80211: Add packet coalesce support

In most cases, host that receives IPv4 and IPv6 multicast/broadcast
packets does not do anything with these packets. Therefore the
reception of these unwanted packets causes unnecessary processing
and power consumption.

Packet coalesce feature helps to reduce number of received
interrupts to host by buffering these packets in firmware/hardware
for some predefined time. Received interrupt will be generated when
one of the following events occur.
a) Expiration of hardware timer whose expiration time is set to
maximum coalescing delay of matching coalesce rule.
b) Coalescing buffer in hardware reaches it's limit.
c) Packet doesn't match any of the configured coalesce rules.

This patch adds set/get configuration support for packet coalesce.
User needs to configure following parameters for creating a coalesce
rule.
a) Maximum coalescing delay
b) List of packet patterns which needs to be matched
c) Condition for coalescence. pattern 'match' or 'no match'
Multiple ...