Remove an unnecessary piece of code that does an endianness conversion
but does not use the result. The following warning was reported by
Clang's static analyzer:

  arch/powerpc/sysdev/xics/ics-opal.c:114:2: warning: Value stored to
  'server' is never read [deadcode.DeadStores]
  server = be16_to_cpu(oserver);

'server' was used as a parameter to opal_get_xive() in commit
5c7c1e94 ("powerpc/powernv: Add OPAL ICS backend") when it was
introduced. 'server' was also used in an error message for the call to
opal_get_xive().

'server' was always later set by a call to ics_opal_mangle_server()
before being used.

Commit bf8e0f89 ("powerpc/powernv: Fix endian issues in OPAL ICS
backend") used a new variable 'oserver' as the parameter to
opal_get_xive() instead of 'server' for endian correctness. It also
removed 'server' from the error message for the call to opal_get_xive().

Fix the warning by removing the server variable assignment.

Fixes: bf8e0f89 ("powerpc/powernv: Fix endian issues in OPAL ICS backend")
Reviewed-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Gautam Menghani <gautam@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230731115543.36991-1-gautam@linux.ibm.com