ARM: dts: renesas: r8a73a4: Fix external clocks and clock rate

ARM: dts: renesas: r8a73a4: Fix external clocks and clock rate

[ Upstream commit 090c4094574705b0afc7d37825cdc5d06f0e7e02 ]

External clocks should be defined as zero-Hz clocks in the SoC .dtsi,
and overridden in the board .dts when present.

Correct the clock rate of extal1 from 25 to 26 MHz, to match the crystal
oscillator present on the APE6-EVM board.

Fixes: a76809a329d6ebae ("ARM: shmobile: r8a73a4: Common clock framework DT description")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/1692bc8cd465d62168cbf110522ad62a7af3f606.1705315614.git.geert+renesas@glider.be
Signed-off-by: Sasha Levin <sashal@kernel.org>