linux-user: Remove pointless NULL check in clock_adjtime handling

linux-user: Remove pointless NULL check in clock_adjtime handling

In the code for TARGET_NR_clock_adjtime, we set the pointer phtx to
the address of the local variable htx.  This means it can never be
NULL, but later in the code we check it for NULL anyway.  Coverity
complains about this (CID 1507683) because the NULL check comes after
a call to clock_adjtime() that assumes it is non-NULL.

Since phtx is always &htx, and is used only in three places, it's not
really necessary.  Remove it, bringing the code structure in to line
with that for TARGET_NR_clock_adjtime64, which already uses a simple
'&htx' when it wants a pointer to 'htx'.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230623144410.1837261-1-peter.maydell@linaro.org