Checks the font semaphore and, if the semaphore is not already set, sets the semaphore and returns the "success" result. If the font semaphore has already been set by another process (GD driver), this function returns the "failure" result.
Return values have the following content:
SYD_BT_FNT_SMPH_SUCCESS
Access to BootROM possible
SYD_BT_FNT_SMPH_FAILURE
Access to BootROM impossible
NOTE
If font data is gotten without acquiring the semaphore, an undefined value may be returned.