riscv: fp: add missing __user pointer annotations

The __user annotations were removed from the {save,restore}_fp_state()
function signatures by commit 007f5c35 ("Refactor FPU code in
signal setup/return procedures"), but should be present, and sparse
warns when they are not applied.  Add them back in.

This change should have no functional impact.
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Fixes: 007f5c35 ("Refactor FPU code in signal setup/return procedures")
Cc: Alan Kao <alankao@andestech.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

arch/riscv/kernel/signal.c

@@ -26,7 +26,7 @@ struct rt_sigframe {
 
 #ifdef CONFIG_FPU
 static long restore_fp_state(struct pt_regs *regs,
-			     union __riscv_fp_state *sc_fpregs)
+			     union __riscv_fp_state __user *sc_fpregs)
 {
 	long err;
 	struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
@@ -53,7 +53,7 @@ static long restore_fp_state(struct pt_regs *regs,
 }
 
 static long save_fp_state(struct pt_regs *regs,
-			  union __riscv_fp_state *sc_fpregs)
+			  union __riscv_fp_state __user *sc_fpregs)
 {
 	long err;
 	struct __riscv_d_ext_state __user *state = &sc_fpregs->d;