KVM: arm64: Fix table format for PTP documentation

The documentation build legitimately screams about the PTP
documentation table being misformated.

Fix it by adjusting the table width guides.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Marc Zyngier <maz@kernel.org>

Documentation/virt/kvm/arm/ptp_kvm.rst

@@ -12,14 +12,14 @@ host to the guest using a KVM-specific hypercall.
 This hypercall uses the SMC32/HVC32 calling convention:
 
 ARM_SMCCC_HYP_KVM_PTP_FUNC_ID
-    =============    ==========    ==========
-    Function ID:     (uint32)      0x86000001
-    Arguments:       (uint32)      KVM_PTP_VIRT_COUNTER(0)
-                                   KVM_PTP_PHYS_COUNTER(1)
-    Return Values:   (int32)       NOT_SUPPORTED(-1) on error, or
-                     (uint32)      Upper 32 bits of wall clock time (r0)
-                     (uint32)      Lower 32 bits of wall clock time (r1)
-                     (uint32)      Upper 32 bits of counter (r2)
-                     (uint32)      Lower 32 bits of counter (r3)
-    Endianness:                    No Restrictions.
-    =============    ==========    ==========
+    ==============    ========    =====================================
+    Function ID:      (uint32)    0x86000001
+    Arguments:        (uint32)    KVM_PTP_VIRT_COUNTER(0)
+                                  KVM_PTP_PHYS_COUNTER(1)
+    Return Values:    (int32)     NOT_SUPPORTED(-1) on error, or
+                      (uint32)    Upper 32 bits of wall clock time (r0)
+                      (uint32)    Lower 32 bits of wall clock time (r1)
+                      (uint32)    Upper 32 bits of counter (r2)
+                      (uint32)    Lower 32 bits of counter (r3)
+    Endianness:                   No Restrictions.
+    ==============    ========    =====================================