usb: gadget: f_qc_rndis: Change function name from qcrndis to bam

bam can represent the transport used for the function. Hence change
the name from qcrndis to bam.

Change-Id: Ie153ae9cc00a72287b10623d63f29c08a1154cb9
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>