platform/x86: amd-pmc: Shuffle location of amd_pmc_get_smu_version()

platform/x86: amd-pmc: Shuffle location of amd_pmc_get_smu_version()

When CONFIG_DEBUG_FS is disabled, amd_pmc_get_smu_version() is unused:

  drivers/platform/x86/amd-pmc.c:196:12: warning: unused function 'amd_pmc_get_smu_version' [-Wunused-function]
  static int amd_pmc_get_smu_version(struct amd_pmc_dev *dev)
             ^
  1 warning generated.

Eliminate the warning by moving amd_pmc_get_smu_version() to the
CONFIG_DEBUG_FS block where it is used.

Fixes: b0c07116c894 ("platform/x86: amd-pmc: Avoid reading SMU version at probe time")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20220418213800.21257-1-nathan@kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>