bt-kernel: Add support for Bazel build system

- kernel modules can now be built using Bazel/kleaf for pineapple.
- Added macro that makes it easy to register new modules

Change-Id: If19f9663135342bc36f543b1598231d133c1748f

bt_modules.bzl

@@ -0,0 +1,59 @@
+PWR_PATH = "pwr"
+SLIMBUS_PATH = "slimbus"
+FMRTC_PATH = "rtc6226"
+
+# This dictionary holds all the BT modules included in the bt-kernel
+bt_modules = {}
+
+def register_bt_modules(name, path = None, config_opt = None, srcs = {}, deps = []):
+    """
+    Register modules
+    Args:
+        name: Name of the module (which will be used to generate the name of the .ko file)
+        path: Path in which the source files can be found
+        config_opt: Config name used in Kconfig (not needed currently)
+        srcs: source files and local headers
+        deps: a list of dependent targets
+    """
+    module = struct(
+        name = name,
+        path = path,
+        srcs = srcs,
+        config_opt = config_opt,
+        deps =  deps
+    )
+    bt_modules[name] = module
+
+# --- BT Modules ---
+
+register_bt_modules(
+    name = "btpower",
+    path = PWR_PATH,
+    config_opt = "CONFIG_MSM_BT_PWR",
+    srcs = ["btpower.c"]
+)
+
+register_bt_modules(
+    name = "bt_fm_slim",
+    path = SLIMBUS_PATH,
+    config_opt = "CONFIG_BTFM_SLIM",
+    srcs = [
+        "btfm_slim.c",
+        "btfm_slim.h",
+        "btfm_slim_codec.c",
+        "btfm_slim_slave.c",
+        "btfm_slim_slave.h",
+    ],
+    deps = [":%b_btpower"]
+)
+
+register_bt_modules(
+    name = "radio-i2c-rtc6226-qca",
+    path = FMRTC_PATH,
+    config_opt = "CONFIG_I2C_RTC6226_QCA",
+    srcs = [
+        "radio-rtc6226-common.c",
+        "radio-rtc6226-i2c.c",
+        "radio-rtc6226.h",
+    ]
+)