dm: i2c: use CONFIG_IS_ENABLED macro for DM_I2C/DM_I2C_GPIO

Use CONFIG_IS_ENABLED() macro, which provides more convenient
way to check $(SPL)DM_I2C/$(SPL)DM_I2C_GPIO configs
for both SPL and U-Boot proper.

CONFIG_IS_ENABLED(DM_I2C) expands to:
- 1 if CONFIG_SPL_BUILD is undefined and CONFIG_DM_I2C is set to 'y',
- 1 if CONFIG_SPL_BUILD is defined and CONFIG_SPL_DM_I2C is set to 'y',
- 0 otherwise.

All occurences were replaced automatically using these bash cmds:
$ find . -type f -exec sed -i
     's/ifndef CONFIG_DM_I2C/if !CONFIG_IS_ENABLED(DM_I2C)/g' {} +
$ find . -type f -exec sed -i
    's/ifdef CONFIG_DM_I2C/if CONFIG_IS_ENABLED(DM_I2C)/g' {} +
$ find . -type f -exec sed -i
    's/defined(CONFIG_DM_I2C)/CONFIG_IS_ENABLED(DM_I2C)/g' {} +
$ find . -type f -exec sed -i
    's/ifndef CONFIG_DM_I2C_GPIO/if !CONFIG_IS_ENABLED(DM_I2C_GPIO)/g' {} +
$ find . -type f -exec sed -i
    's/ifdef CONFIG_DM_I2C_GPIO/if CONFIG_IS_ENABLED(DM_I2C_GPIO)/g' {} +
$ find . -type f -exec sed -i
    's/defined(CONFIG_DM_I2C_GPIO)/CONFIG_IS_ENABLED(DM_I2C_GPIO)/g' {} +

Reviewed-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Igor Opaniuk <igor.opaniuk@foundries.io>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>

include/config_fallbacks.h

@@ -46,7 +46,7 @@
 #define CONFIG_SYS_MAXARGS	16
 #endif
 
-#ifdef CONFIG_DM_I2C
+#if CONFIG_IS_ENABLED(DM_I2C)
 # ifdef CONFIG_SYS_I2C
 #  error "Cannot define CONFIG_SYS_I2C when CONFIG_DM_I2C is used"
 # endif