ARM: dts: shmobile: Update CMT1 compatible values

New compatible values were introduced for the 48-bit CMT devices on
SH-Mobile AG5 and R-Mobile A1, and the old "cmt-48"-based values were
deprecated.  However, the actual DTS files were never updated.

See also commits:
  - 81b604c3 ("dt-bindings: timer: renesas, cmt: Update CMT1 on
    sh73a0 and r8a7740"),
  - 8c1afba2 ("clocksource/drivers/sh_cmt: r8a7740 and sh73a0
    SoC-specific match"),
  - 19d60845 ("clocksource/drivers/sh_cmt: Document "cmt-48" as
    deprecated").

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200420151553.22975-1-geert+renesas@glider.be