package/libftdi: rename patch with the proper naming convention

As reported by check-package (by calling it directly):
use name <number>-<description>.patch

Output of:
make libftdi-dirclean libftdi-patch | grep 'Patching\|Applying'

Before:
>>> libftdi 0.20 Patching
Applying 0001_pkgconfig_libusb.patch using patch:
Applying 0002-libftdi.pc-requires-libusb-fix-static-build.patch using patch:

After:
>>> libftdi 0.20 Patching
Applying 0001-pkgconfig_libusb.patch using patch:
Applying 0002-libftdi.pc-requires-libusb-fix-static-build.patch using patch:

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>