lib: crc32: put the crc_table variable into efi_runtime_rodata section

When compiling with LTO, the compiler fails with an error saying that
`crc_table` causes a section type conflict with `efi_var_buf`.

This is because both are declared to be in the same section (via macro
`__efi_runtime_data`), but one is const while the other is not.

Put this variable into the section .rodata.efi_runtime, instead of
.data.efi_runtime, via macro __efi_runtime_rodata.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Heinrich Schuchardt <xypron.gpk@gmx.de>