serial: msm_geni_serial: Separate earlyconsole functionality

This patch separates out earlyconsole functionality from kernel
console driver .The common driver apis used by earlyconsole are
defined internally in earlyconsole driver. The objective is to
make earlyconsole as static compiled driver and keep rest of the
driver functionality as a loadable module.

Change-Id: Ib28472794f947937e745226c8e6d25eb3e246d94
Signed-off-by: Mukesh Kumar Savaliya <msavaliy@codeaurora.org>
Signed-off-by: Vipin Deep Kaur <vkaur@codeaurora.org>