Revert "xen/PVonHVM: fix compile warning in init_hvm_pv_info"

This reverts commit a7be94ac.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/xen/enlighten.c

@@ -1579,7 +1579,7 @@ static void __init xen_hvm_init_shared_info(void)
 
 static void __init init_hvm_pv_info(void)
 {
-	uint32_t ecx, edx, pages, msr, base;
+	uint32_t eax, ebx, ecx, edx, pages, msr, base;
 	u64 pfn;
 
 	base = xen_cpuid_base();