cmake: add toolchain_ld_<name> macros to FindDeprecated

Follow-up: #77887

The macros:
- toolchain_ld_base
- toolchain_ld_baremetal
- toolchain_ld_cpp

was deprecated in 5db1f1ae8f17a5f351e73fcc4aa45d52b2919505 but no check
was added to FindDeprecated.cmake, meaning toolchains still providing
those macros was not getting a proper deprecation warning.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>