Clean up 'inline is not at beginning' warnings for usb storage

Usually we don't care much about 'gcc -W' warnings, but some of us do build
kernels that way to look for problems, and then the fewer warnings we have
to wade through the better. Especially when they are very easy and
non-intrusive to clean up. Which is the case for the following warnings
spewed by drivers/usb/storage/usb.h :

  drivers/usb/storage/usb.h:163: warning: `inline' is not at beginning of
+declaration
  drivers/usb/storage/usb.h:166: warning: `inline' is not at beginning of
+declaration

There's also some precedence for cleaning up these warnings. I've had
a few patches merged in the past that remove exactly this class of
warnings.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>