usb: musb: core: drop redundant checks

In musb_{save|restore}_context() the expression '&musb->endpoints[i]' just
cannot be NULL, so the checks have no sense at all -- after dropping them,
the local variables 'hw_ep' are no longer necessary, so drop them as well.

Found by Linux Verification Center (linuxtesting.org) with the SVACE static
analysis tool.

Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/3f8f60d9-f1b5-6b2c-1222-39b156151a22@omp.ru


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>