efi: efivars: make efivar_supports_writes() return bool

For consistency with the new efivar_is_available() function, change the
return type of efivar_supports_writes() to bool.
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

drivers/firmware/efi/vars.c

@@ -110,7 +110,7 @@ int efivars_unregister(struct efivars *efivars)
 }
 EXPORT_SYMBOL_GPL(efivars_unregister);
 
-int efivar_supports_writes(void)
+bool efivar_supports_writes(void)
 {
 	return __efivars && __efivars->ops->set_variable;
 }

include/linux/efi.h

@@ -1061,7 +1061,7 @@ bool efivar_is_available(void);
 static inline bool efivar_is_available(void) { return false; }
 #endif
 
-int efivar_supports_writes(void);
+bool efivar_supports_writes(void);
 
 int efivar_lock(void);
 int efivar_trylock(void);