Check if PTP operations are supported before calling them.
Check if PTP operations are supported before calling them.

Signed-off-by: Lei Zhang <79648d9aca10df37c1b962af0b65ebfac3e19883@google.com>
Signed-off-by: Linus Walleij <67b0e6e4a7f8300bccd309fb10a9106ef3d7b5b0@df.lth.se>

philipl/libmtp,olunx/libmtp,reverendhomer/libmtp,jemc/libmtp,reverendhomer/libmtp,mmalecki/libmtp,jemc/libmtp,libmtp/libmtp,mmalecki/libmtp,jemc/libmtp,libmtp/libmtp,libmtp/libmtp,reverendhomer/libmtp,reverendhomer/libmtp,mmalecki/libmtp,philipl/libmtp,olunx/libmtp,olunx/libmtp,jemc/libmtp,philipl/libmtp