firmware: bcm47xx_nvram: Correct size_t printf format

When building on a 64-bit host, we will get warnings like those:

drivers/firmware/broadcom/bcm47xx_nvram.c:103:3: note: in expansion of macro 'pr_err'
   pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
   ^~~~~~
drivers/firmware/broadcom/bcm47xx_nvram.c:103:28: note: format string is defined here
   pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
                           ~^
                           %li

Use %zu instead for that purpose.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@linux-mips.org
Cc: joe@perches.com
Cc: Rafał Miłecki <zajec5@gmail.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org