net: ipa: use the right accessor in ipa_endpoint_status_skip()

When extracting the destination endpoint ID from the status in
ipa_endpoint_status_skip(), u32_get_bits() is used.  This happens to
work, but it's wrong: the structure field is only 8 bits wide
instead of 32.

Fix this by using u8_get_bits() to get the destination endpoint ID.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>