gpio: aspeed: Remove reference to clock name in debounce warning message

HPLL is in fact not the clock we need. Remove the description of which clock we
failed to find a phandle to in order to avoid any further error.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Acked-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>