riscv: Fix sparse warning about different address spaces

We did not propagate the __user attribute of the pointers in
__get_kernel_nofault() and __put_kernel_nofault(), which results in
sparse complaining:

>> mm/maccess.c:41:17: sparse: sparse: incorrect type in argument 2 (different address spaces) @@     expected void const [noderef] __user *from @@     got unsigned long long [usertype] * @@
   mm/maccess.c:41:17: sparse:     expected void const [noderef] __user *from
   mm/maccess.c:41:17: sparse:     got unsigned long long [usertype] *

So fix this by correctly casting those pointers.

Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Suggested-by: Al Viro <[email protected]>
Fixes: f6bff78 ("riscv: uaccess: use 'asm_goto_output' for get_user()")
Cc: [email protected]
Signed-off-by: Alexandre Ghiti <[email protected]>
Reviewed-by: Cyril Bur <[email protected]>
Link: https://lore.kernel.org/r/20250903-dev-alex-sparse_warnings_v1-v1-2-7e6350beb700@rivosinc.com
Signed-off-by: Paul Walmsley <[email protected]>

Author: Alexandre Ghiti

arch/riscv/include/asm/uaccess.h

@@ -438,10 +438,10 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n)
 }
 
 #define __get_kernel_nofault(dst, src, type, err_label)			\
-	__get_user_nocheck(*((type *)(dst)), (type *)(src), err_label)
+	__get_user_nocheck(*((type *)(dst)), (__force __user type *)(src), err_label)
 
 #define __put_kernel_nofault(dst, src, type, err_label)			\
-	__put_user_nocheck(*((type *)(src)), (type *)(dst), err_label)
+	__put_user_nocheck(*((type *)(src)), (__force __user type *)(dst), err_label)
 
 static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len)
 {