tpm: fix tpm_bios_log_setup stub prototype

tpm: fix tpm_bios_log_setup stub prototype

A cleanup patch changed the prototype of the regular tpm_bios_log_setup
function, but not that of the stub that is used when the TPM is disabled,
causing a harmless build warning:

drivers/char/tpm/tpm-chip.c: In function 'tpm1_chip_register':
drivers/char/tpm/tpm-chip.c:287:38: error: passing argument 1 of 'tpm_bios_log_setup' discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
  chip->bios_dir = tpm_bios_log_setup(dev_name(&chip->dev));
In file included from ../drivers/char/tpm/tpm-chip.c:30:0:
../drivers/char/tpm/tpm_eventlog.h:83:31: note: expected 'char *' but argument is of type 'const char *'
 static inline struct dentry **tpm_bios_log_setup(char *name)

This changes the stub function to match the normal prototype,
avoiding that warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: aca8db8088c3 ("tpm: Get rid of devname")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>