clk: en7523: introduce chip_scu regmap

Introduce chip_scu regmap pointer since EN7581 SoC will access chip-scu
memory area via a syscon node. Remove first memory region mapping
for EN7581 SoC. This patch does not introduce any backward incompatibility
since the dts for EN7581 SoC is not upstream yet.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/20241112-clk-en7581-syscon-v2-4-8ada5e394ae4@kernel.org


Signed-off-by: Stephen Boyd <sboyd@kernel.org>