ARM: dts: r8a7793: Reduce size of thermal registers

Reduce size of thermal registers in DT for r8a7793 (R-Car M3-N) SoC.

According to the "User's Manual: Hardware" v2.00 the registers at base
0xe61f0000 extend to an offset of 0x10, rather than 0x14 which is the case
on the r8a73a4 (R-Mobile APE6).

This should not have any runtime affect as mapping granularity is PAGE_SIZE.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>