ARM: dts: renesas: Reinstate R8A779H0 V4M U-Boot DTs

ARM: dts: renesas: Reinstate R8A779H0 V4M U-Boot DTs

Commit 63da3a795e86 ("ARM: dts: renesas: Drop R8A779H0 V4M DTs with OF_UPSTREAM counterparts")
removed unnecessary V4H DTs from arch/arm/dts , but in the process
also incorrectly dropped the -u-boot.dtsi U-Boot extras. Reinstate
those extras.

Due to DT file name change for the R8A779H0 V4M Gray Hawk, update
the r8a779h0-gray-hawk-u-boot.dtsi filename to newly matching
r8a779h0-gray-hawk-single-u-boot.dtsi .

Align r8a779h0-u-boot.dtsi with clean up commits
1487c34efa7b ("arm64: dts: renesas: Deduplicate extalr_clk bootph-all")
dd8f57ed2f0b ("ARM: dts: renesas: Drop most of bootph-* tags")

Fixes: 63da3a795e86 ("ARM: dts: renesas: Drop R8A779H0 V4M DTs with OF_UPSTREAM counterparts")
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>