riscv: Fixup obvious bug for fp-regs reset

CSR_MISA is defined in Privileged Architectures' spec: 3.1.1 Machine
ISA Register misa. Every bit:1 indicate a feature, so we should beqz
reset_done when there is no F/D bit in csr_misa register.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
[paul.walmsley@sifive.com: fix typo in commit message]
Fixes: 9e80635 ("riscv: clear the instruction cache and all registers when booting")
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

arch/riscv/kernel/head.S

@@ -251,7 +251,7 @@ ENTRY(reset_regs)
 #ifdef CONFIG_FPU
 	csrr	t0, CSR_MISA
 	andi	t0, t0, (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D)
-	bnez	t0, .Lreset_regs_done
+	beqz	t0, .Lreset_regs_done
 
 	li	t1, SR_FS
 	csrs	CSR_STATUS, t1