eal/linux: fix build
eal/linux: fix build

Compilation fails in some distributions because of missing unistd.h
needed for pread/pwrite (seen with Suse):
	lib/librte_eal/linuxapp/eal/eal_pci_uio.c:62:2:
	error: implicit declaration of function ‘pread’

Fixes: 4a499c649590 ("eal/linux: enable uio_pci_generic support")

Signed-off-by: Thomas Monjalon <ee2fa8b2681c737f775687e475dcbf2028a412f1@6wind.com>
Acked-by: David Marchand <f28529695cfa9e3e1eb84e7072aa626af4abb18e@6wind.com>

phermansson/dpdk,phermansson/dpdk,phermansson/dpdk,phermansson/dpdk