docs: KVM: Fix register ID of SPSR_FIQ

Fixes the register ID of SPSR_FIQ.

SPSR_FIQ is a 64-bit register and the 64-bit register size mask is
0x0030000000000000ULL.

Fixes: fd3bc912 ("KVM: Documentation: Document arm64 core registers in detail")
Signed-off-by: Takahiro Itazuri <itazur@amazon.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230606154628.95498-1-itazur@amazon.comSigned-off-by: Oliver Upton <oliver.upton@linux.dev>

Documentation/virt/kvm/api.rst

@@ -2592,7 +2592,7 @@ Specifically:
   0x6030 0000 0010 004a SPSR_ABT    64  spsr[KVM_SPSR_ABT]
   0x6030 0000 0010 004c SPSR_UND    64  spsr[KVM_SPSR_UND]
   0x6030 0000 0010 004e SPSR_IRQ    64  spsr[KVM_SPSR_IRQ]
-  0x6060 0000 0010 0050 SPSR_FIQ    64  spsr[KVM_SPSR_FIQ]
+  0x6030 0000 0010 0050 SPSR_FIQ    64  spsr[KVM_SPSR_FIQ]
   0x6040 0000 0010 0054 V0         128  fp_regs.vregs[0]    [1]_
   0x6040 0000 0010 0058 V1         128  fp_regs.vregs[1]    [1]_
   ...