linux-user/sparc: Remove unneeded checks of 'err' from sparc64_get_context()

linux-user/sparc: Remove unneeded checks of 'err' from sparc64_get_context()

Unlike the kernel macros, our __get_user() and __put_user() do not
return a failure code.  Kernel code typically has a style of
  err |= __get_user(...); err |= __get_user(...);
and then checking err at the end.  In sparc64_get_context() our
version of the code dropped the accumulating into err but left the
"if (err) goto do_sigsegv" checks, which will never be taken. Delete
unnecessary if()s.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20201106152738.26026-3-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>