soc: keystone: Merge into ti specific directory

Merge drivers/soc/keystone/ into drivers/soc/ti/
and convert CONFIG_TI_KEYSTONE_SERDES into Kconfig.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/soc/ti/Makefile b/drivers/soc/ti/Makefile
index 63e21aaa..4ec04ee 100644
--- a/drivers/soc/ti/Makefile
+++ b/drivers/soc/ti/Makefile
@@ -1,5 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0+
-#
-# TI K3 SOC drivers
-#
+
 obj-$(CONFIG_TI_K3_NAVSS_RINGACC)	+= k3-navss-ringacc.o
+obj-$(CONFIG_TI_KEYSTONE_SERDES)	+= keystone_serdes.o