virt: acrn: Replace obsolete memalign() with posix_memalign()

virt: acrn: Replace obsolete memalign() with posix_memalign()

memalign() is obsolete according to its manpage.

Replace memalign() with posix_memalign() and remove malloc.h include
that was there for memalign().

As a pointer is passed into posix_memalign(), initialize *p to NULL
to silence a warning about the function's return value being used as
uninitialized (which is not valid anyway because the error is properly
checked before p is returned).

Signed-off-by: Deming Wang <wangdeming@inspur.com>
Link: https://lore.kernel.org/r/20230412073041.2168-1-wangdeming@inspur.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>