phy: exynos5-usbdrd: Add 26MHz ref clk support

phy: exynos5-usbdrd: Add 26MHz ref clk support

Modern Exynos chips (like Exynos850) might have 26 MHz OSCCLK external
clock, which is also used as a PHY reference clock. For some USB PHY
controllers (e.g USB DRD PHY block on Exynos850) there is no need to set
the refclk frequency at all (and corresponding bits in CLKRSTCTRL[7:5]
are marked RESERVED), so that value won't be set in the driver. But
even in that case, 26 MHz support still has to be added, otherwise
exynos5_rate_to_clk() fails, which leads in turn to probe error.

Add the correct value for 26MHz refclk to make it possible to add
support for new Exynos USB DRD PHY controllers.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230819031731.22618-6-semen.protsenko@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>