CP-23903: Allow user to set system enclosure asset tag for VM
CP-23903: Allow user to set system enclosure asset tag for VM

1) Add enclosure-asset-tag to generic-bios-strings.
2) Add a size limit of 512 chars for bios_strings value.

Signed-off-by: Sharad Yadav <0ab5d8dd51ae0f2f9ed283cbbbb7a94d110e3347@citrix.com>

euanh/xen-api,srowe/xen-api,srowe/xen-api,euanh/xen-api,euanh/xen-api,srowe/xen-api,euanh/xen-api,srowe/xen-api,srowe/xen-api,euanh/xen-api,euanh/xen-api