Set the carrier offset correctly using the default mclk values.

Add function m88rs2000_get_mclk to calculate the mclk value
against crystal frequency which will later be used for
other functions.

Add function m88rs2000_set_carrieroffset to calculate
and set the offset value.

variable offset becomes a signed value.

Register 0x86 is set the appropriate value according to
remainder value of frequency % 192857 calculation as
shown.
Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Cc: stable@vger.kernel.org # v3.9+
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>