usb: gadget: add zero length packet support
usb: gadget: add zero length packet support

Add support to DIAG and serial functions to send the zlp packet
if the transfer ends with multiple's of maxpacket size

CRs-fixed: 213416

Signed-off-by: Velempati Chiranjeevi <5819bdcf93de5445d39d03d2cf6f0bbf7275bda4@qualcomm.com>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas