x86: use brk allocation for DMI

Impact: use new interface instead of previous ad hoc implementation

Use extend_brk() to allocate memory for DMI rather than having an
ad-hoc allocator.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/kernel/setup.c

@@ -215,12 +215,6 @@ unsigned long mmu_cr4_features = X86_CR4_PAE;
 /* Boot loader ID as an integer, for the benefit of proc_dointvec */
 int bootloader_type;
 
-/*
- * Early DMI memory
- */
-int dmi_alloc_index;
-char dmi_alloc_data[DMI_MAX_DATA];
-
 /*
  * Setup options
  */