qemu-options.hx: Specify the units for -machine kvm_shadow_mem

The -machine kvm_shadow_mem option takes a size in bytes; say
so explicitly in its documentation.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reported-by: Tobi (github.com/tobimensch)
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

qemu-options.hx

@@ -35,7 +35,7 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
     "                kernel_irqchip=on|off controls accelerated irqchip support\n"
     "                kernel_irqchip=on|off|split controls accelerated irqchip support (default=off)\n"
     "                vmport=on|off|auto controls emulation of vmport (default: auto)\n"
-    "                kvm_shadow_mem=size of KVM shadow MMU\n"
+    "                kvm_shadow_mem=size of KVM shadow MMU in bytes\n"
     "                dump-guest-core=on|off include guest memory in a core dump (default=on)\n"
     "                mem-merge=on|off controls memory merge support (default: on)\n"
     "                iommu=on|off controls emulated Intel IOMMU (VT-d) support (default=off)\n"