drm: radeon: ni_dpm: Fix unused variable warning when CONFIG_ACPI=n

With CONFIG_ACPI=n the following build warning is seen:

drivers/gpu/drm/radeon/ni_dpm.c:3448:31: warning: unused variable 'eg_pi' [-Wunused-variable]

Move the definition of eg_pi inside the CONFIG_ACPI 'if' block.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/ni_dpm.c

@@ -3445,9 +3445,9 @@ static int ni_enable_smc_cac(struct radeon_device *rdev,
 static int ni_pcie_performance_request(struct radeon_device *rdev,
 				       u8 perf_req, bool advertise)
 {
+#if defined(CONFIG_ACPI)
 	struct evergreen_power_info *eg_pi = evergreen_get_pi(rdev);
 
-#if defined(CONFIG_ACPI)
 	if ((perf_req == PCIE_PERF_REQ_PECI_GEN1) ||
             (perf_req == PCIE_PERF_REQ_PECI_GEN2)) {
 		if (eg_pi->pcie_performance_request_registered == false)