libusbg: Add inline to gadget_write_string().
libusbg: Add inline to gadget_write_string().

Add inline to gadget_write_string().

Signed-off-by: Stanislaw Wadas <45c1812d781e6eb1765fa6c6737751add3c95468@samsung.com>

pszewczyk/libusbg,pszewczyk/libusbg