fsi: cleanup extern usage in function definition

Smatch reports these issues
fsi-core.c:395:12: warning: function 'fsi_slave_claim_range'
  with external linkage has definition
fsi-core.c:409:13: warning: function 'fsi_slave_release_range'
  with external linkage has definition

The storage-class-specifier extern is not needed in a
definition, so remove it.
Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20220403140937.3833578-1-trix@redhat.comSigned-off-by: Joel Stanley <joel@jms.id.au>

drivers/fsi/fsi-core.c

@@ -392,8 +392,8 @@ int fsi_slave_write(struct fsi_slave *slave, uint32_t addr,
 }
 EXPORT_SYMBOL_GPL(fsi_slave_write);
 
-extern int fsi_slave_claim_range(struct fsi_slave *slave,
-		uint32_t addr, uint32_t size)
+int fsi_slave_claim_range(struct fsi_slave *slave,
+			  uint32_t addr, uint32_t size)
 {
 	if (addr + size < addr)
 		return -EINVAL;
@@ -406,8 +406,8 @@ extern int fsi_slave_claim_range(struct fsi_slave *slave,
 }
 EXPORT_SYMBOL_GPL(fsi_slave_claim_range);
 
-extern void fsi_slave_release_range(struct fsi_slave *slave,
-		uint32_t addr, uint32_t size)
+void fsi_slave_release_range(struct fsi_slave *slave,
+			     uint32_t addr, uint32_t size)
 {
 }
 EXPORT_SYMBOL_GPL(fsi_slave_release_range);