get_unaligned_le16() is defined in linux/unaligned/access_ok.h header
but it uses symbols which may not be available, leading to build
failures on ia64. Using asm/unaligned.h seem to be the right thing
and used in other drivers.

This fixes below error reported by kbuild test robot

In file included from drivers/usb/host/xhci-pci-renesas.c:9:
>> include/linux/unaligned/access_ok.h:8:28: error: redefinition of 'get_unaligned_le16'
8 | static __always_inline u16 get_unaligned_le16(const void *p)
|                            ^~~~~~~~~~~~~~~~~~
In file included from arch/ia64/include/asm/unaligned.h:5,
from arch/ia64/include/asm/io.h:23,
from arch/ia64/include/asm/smp.h:21,
from include/linux/smp.h:67,
from include/linux/percpu.h:7,
from include/linux/arch_topology.h:9,
from include/linux/topology.h:30,
from include/linux/gfp.h:9,
from include/linux/xarray.h:14,
from include/linux/radix-tree.h:18,
from include/linux/idr.h:15,
from include/linux/kernfs.h:13,
from include/linux/sysfs.h:16,
from include/linux/kobject.h:20,
from include/linux/of.h:17,
from include/linux/irqdomain.h:35,
from include/linux/acpi.h:13,
from drivers/usb/host/xhci-pci-renesas.c:4:
include/linux/unaligned/le_struct.h:7:19: note: previous definition of 'get_unaligned_le16' was here
7 | static inline u16 get_unaligned_le16(const void *p)
|                   ^~~~~~~~~~~~~~~~~~
In file included from drivers/usb/host/xhci-pci-renesas.c:9:
include/linux/unaligned/access_ok.h:13:28: error: redefinition of 'get_unaligned_le32'
13 | static __always_inline u32 get_unaligned_le32(const void *p)
|                            ^~~~~~~~~~~~~~~~~~
In file included from arch/ia64/include/asm/unaligned.h:5,
from arch/ia64/include/asm/io.h:23,
from arch/ia64/include/asm/smp.h:21,
from include/linux/smp.h:67,
from include/linux/percpu.h:7,
from include/linux/arch_topology.h:9,
from include/linux/topology.h:30,
from include/linux/gfp.h:9,
from include/linux/xarray.h:14,
from include/linux/radix-tree.h:18,
from include/linux/idr.h:15,
from include/linux/kernfs.h:13,
from include/linux/sysfs.h:16,
from include/linux/kobject.h:20,
from include/linux/of.h:17,
from include/linux/irqdomain.h:35,
from include/linux/acpi.h:13,
from drivers/usb/host/xhci-pci-renesas.c:4:
include/linux/unaligned/le_struct.h:12:19: note: previous definition of 'get_unaligned_le32' was here

Fixes: 8bd5741e ("usb: renesas-xhci: Add the renesas xhci driver")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20200516162516.385149-1-vkoul@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>