realtek: Optimize kernel configuration for RTL838X

The RTL838X SoCs do not use Aquantia PHYs, remove this.
Also the RTL838X uses a high resolution R4K timer.

Signed-off-by: Birger Koblitz <git@birger-koblitz.de>

target/linux/realtek/rtl838x/config-5.10

-CONFIG_AQUANTIA_PHY=y
 CONFIG_ARCH_32BIT_OFF_T=y
 CONFIG_ARCH_HIBERNATION_POSSIBLE=y
 CONFIG_ARCH_MMAP_RND_BITS_MAX=15
@@ -76,7 +75,7 @@ CONFIG_HARDWARE_WATCHPOINTS=y
 CONFIG_HAS_DMA=y
 CONFIG_HAS_IOMEM=y
 CONFIG_HAS_IOPORT_MAP=y
-# CONFIG_HIGH_RES_TIMERS is not set
+CONFIG_HIGH_RES_TIMERS=y
 CONFIG_HWMON=y
 CONFIG_HZ_PERIODIC=y
 CONFIG_I2C=y
@@ -85,9 +84,8 @@ CONFIG_I2C_BOARDINFO=y
 CONFIG_I2C_CHARDEV=y
 CONFIG_I2C_GPIO=y
 CONFIG_I2C_MUX=y
-CONFIG_I2C_MUX_RTL9300=y
-CONFIG_I2C_RTL9300=y
-CONFIG_I2C_SMBUS=y
+# CONFIG_I2C_RTL9300 is not set
+# CONFIG_I2C_MUX_RTL9300 is not set
 CONFIG_INITRAMFS_SOURCE=""
 CONFIG_IRQCHIP=y
 CONFIG_IRQ_DOMAIN=y