media: si470x: fix printk warnings with clang

Clang doesn't like "%hu" on macros:

	drivers/media/radio/si470x/radio-si470x-i2c.c:414:4: error: format specifies type 'unsigned short' but the argument has type 'int' [-Werror,-Wformat]
	drivers/media/radio/si470x/radio-si470x-i2c.c:417:4: error: format specifies type 'unsigned short' but the argument has type 'int' [-Werror,-Wformat]

Besides that, changeset cbacb5ab ("docs: printk-formats: Stop encouraging use of unnecessary %h[xudi] and %hh[xudi]")
dropped recomendation of using %h.

So, just replace them with "%u".

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>