lib: sbi_ipi: Move initial IPI clear to sbi_ipi_init()

sbi_ipi_init() expects the platform warm init function to clear IPIs
on the local hart, but there is already a generic function to do this.
After this change, none of the existing drivers need a warm init
callback.

Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

platform/fpga/ariane/platform.c

@@ -143,7 +143,7 @@ static int ariane_ipi_init(bool cold_boot)
 			return ret;
 	}
 
-	return aclint_mswi_warm_init();
+	return 0;
 }
 
 /*

platform/fpga/openpiton/platform.c

@@ -174,7 +174,7 @@ static int openpiton_ipi_init(bool cold_boot)
 			return ret;
 	}
 
-	return aclint_mswi_warm_init();
+	return 0;
 }
 
 /*

platform/kendryte/k210/platform.c

@@ -156,7 +156,7 @@ static int k210_ipi_init(bool cold_boot)
 			return rc;
 	}
 
-	return aclint_mswi_warm_init();
+	return 0;
 }
 
 static int k210_timer_init(void)

platform/nuclei/ux600/platform.c

@@ -212,7 +212,7 @@ static int ux600_ipi_init(bool cold_boot)
 			return rc;
 	}
 
-	return aclint_mswi_warm_init();
+	return 0;
 }
 
 static int ux600_timer_init(void)

platform/template/platform.c

@@ -112,7 +112,7 @@ static int platform_ipi_init(bool cold_boot)
 			return ret;
 	}
 
-	return aclint_mswi_warm_init();
+	return 0;
 }
 
 /*