kvmtool: remove reference to <asm/types.h> from BIOS include files

For x86 the files that become the BIOS blob are compiled with -m32.
Although we avoid including any system libraries, we use some headers
from /usr/include, which asks for trouble if compiling on a x86-64
multiarch system (Debian/Ubuntu). Without 32-bit compat headers
installed there, the compiler will not find the right files.
However as the BIOS code is actually a self-contained binary without
any relationship to the Linux userland, it should not use or rely
on Linux system headers.
Replace includes of linux/types.h in BIOS code with asm/bios/types.h,
which simply contains the u{8,16,32,64} data types needed by the code.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>