net: macb: Check for SKBTX_HW_TSTAMP in macb driver

net: macb: Check for SKBTX_HW_TSTAMP in macb driver

Make sure SKBTX_HW_TSTAMP (i.e. SOF_TIMESTAMPING_TX_HARDWARE) has
been enabled for this skb. This is a common practice in handling TX
timestamp. It fixes the issue where normal socks that aren't
expecting a timestamp will not wake up on select.

Fixed if statement, modified commit description and tested.
- Harini

Signed-off-by: Paul Thomas <pthomas8589@gmail.com>
Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>