tests: arch: arm: fix -Wformat error

[tpambor]

Cast _vector_start to uint32_t to match format specifier.

/home/user/west_workspace/zephyr/tests/arch/arm/arm_sw_vector_relay/src/arm_sw_vector_relay.c: In function 'arm_sw_vector_relay_test_arm_sw_vector_relay':
/home/user/west_workspace/zephyr/tests/arch/arm/arm_sw_vector_relay/src/arm_sw_vector_relay.c:71:22: error: format '%x' expects argument of type 'unsigned int', but argument 8 has type 'char *' [-Werror=format=]
   71 |                      "vector table pointer not pointing to vector start, 0x%x, 0x%x\n",
      |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   72 |                      _vector_table_pointer, _vector_start);
      |                                             ~~~~~~~~~~~~~
      |                                             |
      |                                             char *

Part of #96968

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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