usb: gadget: define free_ep_req as universal function

commit 079fe5a6da616891cca1a26e803e1df2a87e9ae5 upstream.

This function is shared between gadget functions, so this avoid unnecessary
duplicated code and potentially avoid memory leaks.

Change-Id: I8409108811080e79da98a5d1d616dc64cc52c79d
Reviewed-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: 0446437c8bb63e03e05fa0024abc1bb27eaf037c
Git-repo: https://android.googlesource.com/kernel/msm


(cravin@codeaurora.org: resolved minor conflicts)
Signed-off-by: Srinivasa Rao Kuppala <srkupp@codeaurora.org>
Signed-off-by: Chetan C R <cravin@codeaurora.org>