arm_interface: Add missing fpsr/tpidr members to the ThreadContext struct

Internally within the kernel, it also includes a member variable for the
floating-point status register, and TPIDR, so we should do the same here to match
it.

While we're at it, also fix up the size of the struct and add a static
assertion to ensure it always stays the correct size.

src/core/arm/arm_interface.h

@@ -22,10 +22,16 @@ public:
         std::array<u64, 31> cpu_registers;
         u64 sp;
         u64 pc;
-        u64 pstate;
+        u32 pstate;
+        std::array<u8, 4> padding;
         std::array<u128, 32> vector_registers;
-        u64 fpcr;
+        u32 fpcr;
+        u32 fpsr;
+        u64 tpidr;
     };
+    // Internally within the kernel, it expects the AArch64 version of the
+    // thread context to be 800 bytes in size.
+    static_assert(sizeof(ThreadContext) == 0x320);
 
     /// Runs the CPU until an event happens
     virtual void Run() = 0;