Convert CONFIG_LPUART et al to Kconfig

This converts the following to Kconfig:
   CONFIG_LPUART
   CONFIG_LPUART_32B_REG

And note that CONFIG_LPUART_32B_REG is unused in code.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/ls1028aqds_tfa_lpuart_defconfig b/configs/ls1028aqds_tfa_lpuart_defconfig
index 1d0e303..0f4a33c 100644
--- a/configs/ls1028aqds_tfa_lpuart_defconfig
+++ b/configs/ls1028aqds_tfa_lpuart_defconfig
@@ -22,7 +22,6 @@
 CONFIG_FIT_VERBOSE=y
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_OF_STDOUT_VIA_ALIAS=y
-CONFIG_SYS_EXTRA_OPTIONS="LPUART"
 CONFIG_BOOTDELAY=10
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0 earlycon=uart8250,mmio,0x21c0500 ramdisk_size=0x2000000 default_hugepagesz=2m hugepagesz=2m hugepages=256 video=1920x1080-32@60 cma=256M"
@@ -90,6 +89,7 @@
 CONFIG_SPECIFY_CONSOLE_INDEX=y
 CONFIG_DM_SERIAL=y
 CONFIG_FSL_LPUART=y
+CONFIG_LPUART=y
 CONFIG_SPI=y
 CONFIG_DM_SPI=y
 CONFIG_FSL_DSPI=y