[PATCH] fix "ACPI: Processor native C-states using MWAIT"

This patch breaks C-state discovery on my IBM IntelliStation Z30 because
the return value of acpi_processor_get_power_info_fadt is not assigned to
"result" in the case that acpi_processor_get_power_info_cst returns
-ENODEV.  Thus, if ACPI provides C-state data via the FADT and not _CST (as
is the case on this machine), we incorrectly exit the function with -ENODEV
after reading the FADT.  The attached patch sets the value of result so
that we don't exit early.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Acked-by: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
Acked-by: "Brown, Len" <len.brown@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/acpi/processor_idle.c

@@ -962,7 +962,7 @@ static int acpi_processor_get_power_info(struct acpi_processor *pr)
 
 	result = acpi_processor_get_power_info_cst(pr);
 	if (result == -ENODEV)
-		acpi_processor_get_power_info_fadt(pr);
+		result = acpi_processor_get_power_info_fadt(pr);
 
 	if (result)
 		return result;