msm: usb_bam: remove unused uninitialized variable

Remove the local variable 'bam' in usb_bam_sps_events()
along with the not very useful log message that was accessing
it uninitialized.

Change-Id: I07bd5f7c14463af17311ee6a1092f7b89bf017d1
Signed-off-by: Jack Pham <jackp@codeaurora.org>