hvmloader/smbios: Change strncpy to memcpy for anchor strings

hvmloader/smbios: Change strncpy to memcpy for anchor strings

Coverity complains about the use of strncpy() to completely fill the anchor
strings, resulting in an unterminated string.

Although the strncpy result is correct, the anchor strings are not strings in
the C sense, and use of memcpy is the prevaling style elsewhere in hvmloader
anyway.

While tidying up the style in this function, also remove some trailing
whitespace and gratuitous cast.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Keir Fraser <keir@xen.org>