x86/platform/uv: Mark uv_min_hub_revision_id static

This variable is only used inside x2apic_uv_x and not even declared
in a header.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Not-acked-by:  Dimitri Sivanich <sivanich@hpe.com>
Cc: Russ Anderson <rja@hpe.com>
Link: https://lkml.kernel.org/r/20200504171527.2845224-8-hch@lst.de

arch/x86/kernel/apic/x2apic_uv_x.c

@@ -48,8 +48,7 @@ static struct {
 	unsigned int gnode_shift;
 } uv_cpuid;
 
-int uv_min_hub_revision_id;
-EXPORT_SYMBOL_GPL(uv_min_hub_revision_id);
+static int uv_min_hub_revision_id;
 
 unsigned int uv_apicid_hibits;
 EXPORT_SYMBOL_GPL(uv_apicid_hibits);