of/irq: do irq resolution in platform_get_irq_byname()

The commit 9ec36caf
"of/irq: do irq resolution in platform_get_irq" from Rob Herring -
moves resolving of the interrupt resources in platform_get_irq().
But this solution isn't complete because platform_get_irq_byname()
need to be modified the same way.

Hence, fix it by adding interrupt resolution code at the
platform_get_irq_byname() function too.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Rob Herring <robh@kernel.org>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Thierry Reding <thierry.reding@gmail.com>

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>