esp32: counter: samples: fix build config

Remove unnecessary build config and rename
Kconfig build variable.

Signed-off-by: Glauber Maroto Ferreira <glauber.ferreira@espressif.com>
diff --git a/samples/drivers/counter/alarm/Kconfig b/samples/drivers/counter/alarm/Kconfig
index 6fb8b47..030a80b 100644
--- a/samples/drivers/counter/alarm/Kconfig
+++ b/samples/drivers/counter/alarm/Kconfig
@@ -11,8 +11,4 @@
 	bool
 	default y if BOARD_ATSAMD20_XPRO
 
-config COUNTER_ESP32
-	bool
-	default y if SOC_ESP32 || SOC_ESP32S2
-
 source "Kconfig.zephyr"
diff --git a/samples/drivers/counter/alarm/src/main.c b/samples/drivers/counter/alarm/src/main.c
index 99eebab..ebb3258 100644
--- a/samples/drivers/counter/alarm/src/main.c
+++ b/samples/drivers/counter/alarm/src/main.c
@@ -29,7 +29,7 @@
 #define TIMER DT_NODELABEL(counter0)
 #elif defined(CONFIG_COUNTER_XLNX_AXI_TIMER)
 #define TIMER DT_INST(0, xlnx_xps_timer_1_00_a)
-#elif defined(CONFIG_COUNTER_ESP32)
+#elif defined(CONFIG_COUNTER_TMR_ESP32)
 #define TIMER DT_NODELABEL(timer0)
 #elif defined(CONFIG_COUNTER_MCUX_CTIMER)
 #define TIMER DT_NODELABEL(ctimer0)