perf/x86/uncore: Fix compilation warning in snb_uncore_imc_init_box()

This patch fixes a compilation problem (unused variable) with the
new SNB/IVB/HSW uncore IMC code.

[ In -v2 we simplify the fix as suggested by Peter Zjilstra. ]
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NStephane Eranian <eranian@google.com>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140311235329.GA28624@quadSigned-off-by: NIngo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/perf_event_intel_uncore.c

@@ -1722,15 +1722,16 @@ static struct attribute_group snb_uncore_imc_format_group = {
 static void snb_uncore_imc_init_box(struct intel_uncore_box *box)
 {
 	struct pci_dev *pdev = box->pci_dev;
-	u32 addr_lo, addr_hi;
+	int where = SNB_UNCORE_PCI_IMC_BAR_OFFSET;
 	resource_size_t addr;
+	u32 pci_dword;
 
-	pci_read_config_dword(pdev, SNB_UNCORE_PCI_IMC_BAR_OFFSET, &addr_lo);
-	addr = addr_lo;
+	pci_read_config_dword(pdev, where, &pci_dword);
+	addr = pci_dword;
 
 #ifdef CONFIG_PHYS_ADDR_T_64BIT
-	pci_read_config_dword(pdev, SNB_UNCORE_PCI_IMC_BAR_OFFSET+4, &addr_hi);
-	addr = ((resource_size_t)addr_hi << 32) | addr_lo;
+	pci_read_config_dword(pdev, where + 4, &pci_dword);
+	addr |= ((resource_size_t)pci_dword << 32);
 #endif
 
 	addr &= ~(PAGE_SIZE - 1);