arch/aarch64: fix storage size for fpsr and fpcr

FPSR and FPCR registers are 32-bit wide.

Reviewed-by: Claudio Fontana <claudio.fontana@huawei.com>
Signed-off-by: Vladimir Murzin <murzin.v@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

arch/aarch64/processor.hh

@@ -58,8 +58,8 @@ inline u64 ticks()
 
 struct fpu_state {
     __uint128_t vregs[32];
-    unsigned long fpsr;
-    unsigned long fpcr;
+    u32 fpsr;
+    u32 fpcr;
 };
 
 inline void fpu_state_save(fpu_state *s)