usb: gserial: Add support to use multiple transport funcs
usb: gserial: Add support to use multiple transport funcs

Currently driver supports multiple com ports over single transport
layer. Add support to support multiple com ports over multiple
transport layers

Change-Id: I43f88b3f809eff8f99d73be86ff8bbd550cdff2f
Signed-off-by: Vamsi Krishna <47b0e29304cd078485ecf21b4f20d61eb25fd047@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