usb: gadget: ncm: Fix string data index definition
usb: gadget: ncm: Fix string data index definition

Commit 489895b107fbf9971090899f433f9d65d052a716 renamed the
local definition of STRING_DATA_IDX to NCM_STRING_DATA_IDX
to avoid a namespace conflict, but the corresponding usage
sites have not been updated.

Change-Id: Ic1b6671d3687a21f399c26b557a02a55a8e27cfe
Signed-off-by: Stepan Moskovchenko <4b3f23b045e38e54cffd83d34440316666b35af9@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