target/arm: Select SEMIHOSTING when using TCG

Semihosting has been made a 'default y' entry in Kconfig, which does
not work because when building --without-default-devices, the
semihosting code would not be available.

Make semihosting unconditional when TCG is present.

Fixes: 29d9efc ("arm/Kconfig: Do not build TCG-only boards on a KVM-only build")
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230508181611.2621-2-farosas@suse.de
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/Kconfig

@@ -1,13 +1,7 @@
 config ARM
     bool
+    select ARM_COMPATIBLE_SEMIHOSTING if TCG
 
 config AARCH64
     bool
     select ARM
-
-# This config exists just so we can make SEMIHOSTING default when TCG
-# is selected without also changing it for other architectures.
-config ARM_SEMIHOSTING
-    bool
-    default y if TCG && ARM
-    select ARM_COMPATIBLE_SEMIHOSTING