soc: ti: pruss: Fix pruss APIs

PRUSS APIs in pruss_driver.h produce lots of compilation errors when
CONFIG_TI_PRUSS is not set.

The errors and warnings,
warning: returning 'void *' from a function with return type 'int' makes
integer from pointer without a cast [-Wint-conversion]
error: expected identifier or '(' before '{' token

Fix these warnings and errors by fixing the return type of pruss APIs as
well as removing the misplaced semicolon from pruss_cfg_xfr_enable()

Fixes: 0211cc1e4fbb ("soc: ti: pruss: Add helper functions to set GPI mode, MII_RT_event and XFR")
Signed-off-by: MD Danish Anwar <[e-mail]>
Reviewed-by: Roger Quadros <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Nishanth Menon <[e-mail]>

include/linux/pruss_driver.h

···
 static inline int pruss_cfg_get_gpmux(struct pruss *pruss,
 				      enum pruss_pru_id pru_id, u8 *mux)
 {
-	return ERR_PTR(-EOPNOTSUPP);
+	return -EOPNOTSUPP;
 }
 
 static inline int pruss_cfg_set_gpmux(struct pruss *pruss,
 				      enum pruss_pru_id pru_id, u8 mux)
 {
-	return ERR_PTR(-EOPNOTSUPP);
+	return -EOPNOTSUPP;
 }
 
 static inline int pruss_cfg_gpimode(struct pruss *pruss,
 				    enum pruss_pru_id pru_id,
 				    enum pruss_gpi_mode mode)
 {
-	return ERR_PTR(-EOPNOTSUPP);
+	return -EOPNOTSUPP;
 }
 
 static inline int pruss_cfg_miirt_enable(struct pruss *pruss, bool enable)
 {
-	return ERR_PTR(-EOPNOTSUPP);
+	return -EOPNOTSUPP;
 }
 
 static inline int pruss_cfg_xfr_enable(struct pruss *pruss,
 				       enum pru_type pru_type,
-				       bool enable);
+				       bool enable)
 {
-	return ERR_PTR(-EOPNOTSUPP);
+	return -EOPNOTSUPP;
 }
 
 #endif /* CONFIG_TI_PRUSS */