tools: PCI: Add 'h' in optstring of getopt()

'h' is a valid option character for the pcitest tool used to print
the pcitest usage.

Add 'h' in optstring of getopt() in order to get rid of "pcitest:
invalid option -- 'h'" warning.

While at that remove unncessary case '?'.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>