hw/i386/pc: factor out pc_cmos_init_floppy()

hw/i386/pc: factor out pc_cmos_init_floppy()

Extract the pc_cmos_init_floppy() function from pc_cmos_init(). The
function sets two RTC registers: floppy drive types (0x10), overwriting
the earlier value in there), and REG_EQUIPMENT_BYTE (0x14), setting bits
in the prior value.

Cc: Jan Tomko <jtomko@redhat.com>
Cc: John Snow <jsnow@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>