RISC-V: Export some expected symbols for modules

These are the ones needed by current allmodconfig, so add them instead
of everything other architectures are exporting -- the rest can be
added on demand later if needed.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

arch/riscv/lib/delay.c

@@ -84,6 +84,7 @@ void __delay(unsigned long cycles)
 	while ((unsigned long)(get_cycles() - t0) < cycles)
 		cpu_relax();
 }
+EXPORT_SYMBOL(__delay);
 
 void udelay(unsigned long usecs)
 {