firmware: drivers/rohm_rpr0521: move I2C ID definition in variant

To reuse the driver on boards where rpr0521 is on another I2C bus

Change-Id: Icfb52e87ac0ec437e5c68a3c3759815bad9b5c37
Signed-off-by: Antonio Borneo <antonio.borneo@st.com>
diff --git a/firmware/os/drivers/rohm_rpr0521/rohm_rpr0521.c b/firmware/os/drivers/rohm_rpr0521/rohm_rpr0521.c
index 55ca4a9..8f2f16a 100644
--- a/firmware/os/drivers/rohm_rpr0521/rohm_rpr0521.c
+++ b/firmware/os/drivers/rohm_rpr0521/rohm_rpr0521.c
@@ -43,9 +43,13 @@
 #error "PROX_IRQ is not defined; please define in variant.h"
 #endif
 
+#ifndef PROX_I2C_BUS_ID
+#define PROX_I2C_BUS_ID     0
+#endif
+
 #define RPR0521_APP_VERSION 3
 
-#define I2C_BUS_ID                              0
+#define I2C_BUS_ID                              PROX_I2C_BUS_ID
 #define I2C_SPEED                               400000
 #define I2C_ADDR                                0x38
 
diff --git a/firmware/variant/lunchbox/inc/variant/variant.h b/firmware/variant/lunchbox/inc/variant/variant.h
index 39c723d..b50f52a 100644
--- a/firmware/variant/lunchbox/inc/variant/variant.h
+++ b/firmware/variant/lunchbox/inc/variant/variant.h
@@ -79,6 +79,7 @@
 
 #define PROX_INT_PIN    GPIO_PB(10)
 #define PROX_IRQ        EXTI15_10_IRQn
+#define PROX_I2C_BUS_ID 0
 
 //define tap sensor threshold
 #define TAP_THRESHOLD   0x01
diff --git a/firmware/variant/nucleo/inc/variant/variant.h b/firmware/variant/nucleo/inc/variant/variant.h
index 375dd7e..e21c5b8 100644
--- a/firmware/variant/nucleo/inc/variant/variant.h
+++ b/firmware/variant/nucleo/inc/variant/variant.h
@@ -60,6 +60,7 @@
 
 #define PROX_INT_PIN    GPIO_PB(10)
 #define PROX_IRQ        EXTI15_10_IRQn
+#define PROX_I2C_BUS_ID 0
 
 //define tap sensor threshold
 #define TAP_THRESHOLD   0x01