gcc-9: properly declare the {pv,hv}clock_page storage

commit 459e3a21535ae3c7a9a123650e54f5c882b8fcbf upstream.

The pvlock_page and hvclock_page variables are (as the name implies)
addresses to pages, created by the linker script.

But we declared them as just "extern u8" variables, which _works_, but
now that gcc does some more bounds checking, it causes warnings like

    warning: array subscript 1 is outside array bounds of ‘u8[1]’

when we then access more than one byte from those variables.

Fix this by simply making the declaration of the variables match
reality, which makes the compiler happy too.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>