apply-patches.sh: add recursivity when scanning patchdir

Recursivity is needed with some tarballs containing debian patches:
.
  debian
    changelog
    control
    patches
      02-COPYRIGHT.patch
[...]

Since we can find some files which are not patches in those directories, only
consider .patch* and .diff* files as valid patches.
Due to recursivity, strip-components option is no more necessary so it has
been removed.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>