usb: gadget: function: f_uac2: fix sparse warnings

usb: gadget: function: f_uac2: fix sparse warnings

this patch fixes following sparse warnings:
f_uac2.c:57:12: warning: symbol 'uac2_name' was not declared. Should it be static?
f_uac2.c:637:36: warning: symbol 'in_clk_src_desc' was not declared. Should it be static?
f_uac2.c:649:36: warning: symbol 'out_clk_src_desc' was not declared. Should it be static?
f_uac2.c:661:39: warning: symbol 'usb_out_it_desc' was not declared. Should it be static?
f_uac2.c:675:39: warning: symbol 'io_in_it_desc' was not declared. Should it be static?
f_uac2.c:689:40: warning: symbol 'usb_in_ot_desc' was not declared. Should it be static?
f_uac2.c:703:40: warning: symbol 'io_out_ot_desc' was not declared. Should it be static?
f_uac2.c:716:34: warning: symbol 'ac_hdr_desc' was not declared. Should it be static?
f_uac2.c:754:34: warning: symbol 'as_out_hdr_desc' was not declared. Should it be static?
f_uac2.c:767:38: warning: symbol 'as_out_fmt1_desc' was not declared. Should it be static?
f_uac2.c:775:32: warning: symbol 'fs_epout_desc' was not declared. Should it be static?
f_uac2.c:785:32: warning: symbol 'hs_epout_desc' was not declared. Should it be static?
f_uac2.c:831:34: warning: symbol 'as_in_hdr_desc' was not declared. Should it be static?
f_uac2.c:844:38: warning: symbol 'as_in_fmt1_desc' was not declared. Should it be static?
f_uac2.c:852:32: warning: symbol 'fs_epin_desc' was not declared. Should it be static?
f_uac2.c:862:32: warning: symbol 'hs_epin_desc' was not declared. Should it be static?
f_uac2.c:1566:21: warning: symbol 'afunc_alloc' was not declared. Should it be static?

Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>