README: remove references on no more used config CONFIG_SYS_RCAR_I2C*

Remove the references in README on CONFIG_SYS_RCAR_I2C_* not use
in U-Boot drivers/i2c/rcar_i2c.c, since commit a4d9aafa ("i2c:
 rcar_i2c: Remove the driver") and commit a06a0ac3 ("i2c: rcar_i2c:
 Add DM and DT capable I2C driver")

Checked by the command: grep -r SYS_RCAR_I2C *
And these CONFIG are only defined in
arch/arm/mach-rmobile/include/mach/rcar-base.h
Signed-off-by: NPatrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>

README

@@ -1632,16 +1632,6 @@ The following options need to be configured:
 		  - activate this driver with CONFIG_SYS_I2C_RCAR
 		  - This driver adds 4 i2c buses
 
-		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
-		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
-		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
-		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
-		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
-		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
-		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
-		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
-		  - CONFIG_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
-
 		- drivers/i2c/sh_i2c.c:
 		  - activate this driver with CONFIG_SYS_I2C_SH
 		  - This driver adds from 2 to 5 i2c buses