riscv: export __cpuid_to_hartid_map

EXPORT_SYMBOL_GPL() is missing for __cpuid_to_hartid_map array.
Export this symbol to allow drivers compiled as modules to use
cpuid_to_hartid_map().

Signed-off-by: Valentina Fernandez <valentina.fernandezalanis@microchip.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>