irqchip/renesas-intc-irqpin: Improve clock error handling and reporting

irqchip/renesas-intc-irqpin: Improve clock error handling and reporting

If the Renesas External IRQ Pin driver cannot find a functional clock,
it prints a warning, .e.g.

    renesas_intc_irqpin fe78001c.interrupt-controller: unable to get clock

and continues, as the clock is optional, depending on the SoC type.
This warning may confuse users.

To fix this, add a flag to indicate that the clock is mandatory or
optional, and add a few more compatible entries:
  - If the clock is mandatory (on R-Mobile A1 or SH-Mobile AG5), a
    missing clock is now treated as a fatal error,
  - If the clock is optional (on R-Car Gen1, or using the generic
    "renesas,intc-irqpin" compatible value), the warning is no longer
    printed.

This requires making struct intc_irqpin_irlm_config more generic by
renaming it to intc_irqpin_config, and adding a flag to indicate if IRLM
is needed.
The new clock flag is merged with the existing shared_irqs boolean into
a bitfield to save space.

Suggested-by: Magnus Damm <magnus.damm@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lkml.kernel.org/r/1448377693-19597-1-git-send-email-geert+renesas@glider.be
Signed-off-by: Jason Cooper <jason@lakedaemon.net>