tree: Check properly if libusb is initialized

The dediprog, developerbox_spi and stlinkv3_spi programmers only check
if the libusb_context is not NULL after the initialization. But
following the API documentation from libusb, the context is undefined
unless the init function returns 0. Fix this by checking the return
value instead of the libusb_context to see if the initialization was
successful.

https://libusb.sourceforge.io/api-1.0/group__libusb__lib.html

Change-Id: Ia45ccd3fa2239dfccd821be46a09c86426cb22e5
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/66460
Reviewed-by: Felix Singer <felixsinger@posteo.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

0 files changed, 0 insertions, 0 deletions