x86/hvm: Correct some address space terminology

x86/hvm: Correct some address space terminology

The function hvm_translate_linear_addr() translates a virtual address to a
linear address, not a linear address to a physical address.  Correct its name.

Both hvm_translate_virtual_addr() and hvmemul_virtual_to_linear() return a
linear address, but a parameter name of paddr is easily confused with paddr_t.
Rename it to linear, to clearly identify the address space, and for
consistency with hvm_virtual_to_linear_addr().

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Tim Deegan <tim@xen.org>
Reviewed-by: Jan Beulich <jbeulich@suse.com>