futex: Remove needless goto's

As stated in the coding style documentation, "if there is no cleanup
needed then just return directly", instead of jumping to a label and
then returning.

Remove such goto's and replace with a return statement.  When there's a
ternary operator on the return value, replace it with the result of the
operation when it is logically possible to determine it by the control
flow.

Signed-off-by: André Almeida <andrealmeid@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200702202843.520764-3-andrealmeid@collabora.com