net: fill in MODULE_DESCRIPTION()s for mpoa

W=1 builds now warn if module is built without a MODULE_DESCRIPTION().
Add descriptions to the Multi-Protocol Over ATM (MPOA) driver.

Signed-off-by: Breno Leitao <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

net/atm/mpc.c

···
 module_init(atm_mpoa_init);
 module_exit(atm_mpoa_cleanup);
 
+MODULE_DESCRIPTION("Multi-Protocol Over ATM (MPOA) driver");
 MODULE_LICENSE("GPL");