USB: gadget: f_audio_source: Set packet size to 256
USB: gadget: f_audio_source: Set packet size to 256

Currently endpoint max packet size is set to 384 bytes. This could
cause crackling noise with USB-DOCK device if USB-DOCK device supports
max iso buffer size of 256 bytes.

Change-Id: I77dcf4ef07af2a7302785f417c4cad51151d501b
Signed-off-by: Vijayavardhan Vennapusa <76e30dc6511df6537bc8f74ebde59f1a6034d162@codeaurora.org>

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