net: ipa: use a bitmap for available endpoints

Similar to the previous patch, replace the 32-bit unsigned used to
track endpoints supported by hardware with a Linux bitmap, to allow
an arbitrary number of endpoints to be represented.

Move ipa_endpoint_deconfig() above ipa_endpoint_config() and use
it in the error path of the latter function.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>