clk: at91: main: warn when the main crystal frequency is not set
clk: at91: main: warn when the main crystal frequency is not set

When the main crystal frequency is not set, the main clock is approximated using
the MAINF value in the CKGR_MCFR register. Warn the user in that case.

Signed-off-by: Alexandre Belloni <a7228e626ecf0022ac91fc1cd8db88e71d0e5e0e@free-electrons.com>
Acked-by: Boris BREZILLON <4e91513d4f418754031d3d36b3fc73980c40a38c@overkiz.com>
Signed-off-by: Mike Turquette <6dab61939fc5e23761050a66932f032dceda5ebf@linaro.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs