i2c: i2c-st: Use %pa to print 'resource_size_t' type

When building multi_v7_defconfig with CONFIG_ARM_LPAE=y the following warning
is seen:

drivers/i2c/busses/i2c-st.c:818:2: warning: format '%x' expects argument of type
'unsigned int', but argument 4 has type 'resource_size_t' [-Wformat=]

Use %pa to print 'resource_size_t' type to fix the warning.

Reported-by: Olof's autobuilder <build@lixom.net>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>