musca: Use the default baud rate

Avoid surprising users. Use the Mbed OS default baud rate. Applications
that want to see TF-M debug prints can both enable and set their baud
rate at the application level. Mbed OS should not turn on TF-M debug
prints nor surprise the user with a non-default baud rate.

Signed-off-by: Jaeden Amero <[email protected]>

Author: Patater

platform/mbed_lib.json

@@ -156,18 +156,6 @@
         }
     },
     "target_overrides": {
-        "ARM_MUSCA_A1_NS": {
-            "stdio-baud-rate": 115200
-        },
-        "ARM_MUSCA_A1_S": {
-            "stdio-baud-rate": 115200
-        },
-        "ARM_MUSCA_B1_NS": {
-            "stdio-baud-rate": 115200
-        },
-        "ARM_MUSCA_B1_S": {
-            "stdio-baud-rate": 115200
-        },
         "EFM32": {
             "stdio-baud-rate": 115200
         },