Same fix as commit c7cf72dc: when 'start' and 'end' are less than a
cacheline apart and 'start' is unaligned we are done after cleaning and
invalidating the first cacheline.

Cc: <stable@kernel.org>
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>