eal: fix x32 build

eal: fix x32 build

Compiling for dpdk x86_x32 gives the following error:

In file included from /usr/include/sys/sysctl.h:63:0,
                 from lib/librte_eal/common/eal_common_timer.c:39:
/usr/include/bits/sysctl.h:19:3: error: #error "sysctl system call is unsupported in x32 kernel"
 # error "sysctl system call is unsupported in x32 kernel"
   ^

Including sysctl.h was added by mistake when merging bsd and linux EAL
timer code. It can be safely removed in this file, fixing the
compilation.

Fixes: 040cf8a411 ("eal: deduplicate timer functions")
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>