ACPI: PAD: Eliminate usage of uninitialized_var() macro

This is an effort to eliminate the uninitialized_var() macro[1].

The use of this macro is the wrong solution because it forces off ANY
analysis by the compiler for a given variable. It even masks "unused
variable" warnings.

Quoted from Linus[2]:

"It's a horrible thing to use, in that it adds extra cruft to the
source code, and then shuts up a compiler warning (even the _reliable_
warnings from gcc)."

The gcc option "-Wmaybe-uninitialized" has been disabled and this change
will not produce any warnnings even with "make W=1".

Link: https://github.com/KSPP/linux/issues/81 # [1]
Link: https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=[e-mail]/ # [2]
Signed-off-by: Jason Yan <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/acpi/acpi_pad.c

···
 	cpumask_var_t tmp;
 	int cpu;
 	unsigned long min_weight = -1;
-	unsigned long uninitialized_var(preferred_cpu);
+	unsigned long preferred_cpu;
 
 	if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
 		return;