package/xenomai: fix build on arc and riscv32

package/xenomai: fix build on arc and riscv32

Fix the following build failures on arc and riscv32:

latency.c: In function 'display':
latency.c:326:21: error: format '%ld' expects argument of type 'long int', but argument 2 has type 'time_t' {aka 'long long int'} [-Werror=format=]
  326 |         ("RTT|  %.2ld:%.2ld:%.2ld  (%s, %Ld us period, "
      |                 ~~~~^
      |                     |
      |                     long int
      |                 %.2lld
  327 |          "priority %d)\n", dt / 3600,
      |                            ~~~~~~~~~
      |                               |
      |                               time_t {aka long long int}

altency.c: In function ‘display’:
altency.c:262:21: error: format ‘%ld’ expects argument of type ‘long int’, but argument 2 has type ‘time_t’ {aka ‘long long int’} [-Werror=format=]
  262 |         ("RTT|  %.2ld:%.2ld:%.2ld  (%s, %Ld us period, "
      |                 ~~~~^
      |                     |
      |                     long int
      |                 %.2lld
  263 |          "priority %d)\n", dt / 3600,
      |                            ~~~~~~~~~
      |                               |
      |                               time_t {aka long long int}

Fixes:
 - http://autobuild.buildroot.org/results/448efe22e8fe058a1b354a3c124874e30b9ce138

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>