arm64: fix .data.rel.ro size assertion when CONFIG_LTO_CLANG

arm64: fix .data.rel.ro size assertion when CONFIG_LTO_CLANG

Commit be2881824ae9 ("arm64/build: Assert for unwanted sections")
introduced an assertion to ensure that the .data.rel.ro section does
not exist.

However, this check does not work when CONFIG_LTO_CLANG is enabled,
because .data.rel.ro matches the .data.[0-9a-zA-Z_]* pattern in the
DATA_MAIN macro.

Move the ASSERT() above the RW_DATA() line.

Fixes: be2881824ae9 ("arm64/build: Assert for unwanted sections")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241106161843.189927-1-masahiroy@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>