string.h: un-fortify memcpy_and_pad

string.h: un-fortify memcpy_and_pad

The way I'd implemented the new helper memcpy_and_pad  with
__FORTIFY_INLINE caused compiler warnings for certain kernel
configurations.

This helper is only used in a single place at this time, and thus
doesn't benefit much from fortification. So simplify the code
by dropping fortification support for now.

Fixes: 01f33c336e2d "string.h: add memcpy_and_pad()"
Signed-off-by: Martin Wilck <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>