RISC-V: Export SBI error to linux error mapping function

All SBI related extensions will not be implemented in sbi.c to avoid
bloating. Thus, sbi_err_map_linux_errno() will be used in other files
implementing that specific extension.

Export the function so that it can be used later.
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/include/asm/sbi.h

@@ -130,6 +130,8 @@ static inline unsigned long sbi_minor_version(void)
 {
 	return sbi_spec_version & SBI_SPEC_VERSION_MINOR_MASK;
 }
+
+int sbi_err_map_linux_errno(int err);
 #else /* CONFIG_RISCV_SBI */
 /* stubs for code that is only reachable under IS_ENABLED(CONFIG_RISCV_SBI): */
 void sbi_set_timer(uint64_t stime_value);

arch/riscv/kernel/sbi.c

@@ -46,7 +46,7 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
 }
 EXPORT_SYMBOL(sbi_ecall);
 
-static int sbi_err_map_linux_errno(int err)
+int sbi_err_map_linux_errno(int err)
 {
 	switch (err) {
 	case SBI_SUCCESS:
@@ -63,6 +63,7 @@ static int sbi_err_map_linux_errno(int err)
 		return -ENOTSUPP;
 	};
 }
+EXPORT_SYMBOL(sbi_err_map_linux_errno);
 
 #ifdef CONFIG_RISCV_SBI_V01
 /**