lib: utils: serial: Add FDT driver for Renesas SCIF

lib: utils: serial: Add FDT driver for Renesas SCIF

Add FDT driver for Renesas SCIF.

    dts example:

    soc: soc {
          ....
            scif0: serial@1004b800 {
                    compatible = "renesas,scif-r9a07g043",
                                 "renesas,scif-r9a07g044";
                    reg = <0 0x1004b800 0 0x400>;
                    interrupts = <412 IRQ_TYPE_LEVEL_HIGH>,
                                 <414 IRQ_TYPE_LEVEL_HIGH>,
                                 <415 IRQ_TYPE_LEVEL_HIGH>,
                                 <413 IRQ_TYPE_LEVEL_HIGH>,
                                 <416 IRQ_TYPE_LEVEL_HIGH>,
                                 <416 IRQ_TYPE_LEVEL_HIGH>;
                    interrupt-names = "eri", "rxi", "txi",
                                      "bri", "dri", "tei";
                    clocks = <&cpg CPG_MOD R9A07G043_SCIF0_CLK_PCK>;
                    clock-names = "fck";
                    power-domains = <&cpg>;
                    resets = <&cpg R9A07G043_SCIF0_RST_SYSTEM_N>;
                    status = "disabled";
            };
          ....
    };

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Anup Patel <anup@brainfault.org>