usb: gadget: android: Use 1024 bytes as MIDI buffer size

Some UDC driver doesn't allow or throw errors when USB request buffer
queued is unaligned i.e. buffer size is not equal to wMaxPacketSize or
multiple of wMaxPacketSize. Fix this issue by using 1024 bytes as MIDI
buffer size instead of 256 bytes.

Change-Id: Ib3493f219de242be56be41d129d128facfe4a8a5
Signed-off-by: Mayank Rana <mrana@codeaurora.org>